共用题干Electromagnetic Energy1 White light seems to be a combination of all colors.The energy that comes from a source of light isnot limited to the kind of energy you can see.Heat is given off by a flame or an electric light.On a cloudy day it is possible to get a sunburn even though you feel cool.Visible light and the kind of energy that produce warmth and sunburn are examples of electromagnetic energy.2 The sun is 93 million miles away from the earth.Yct we can use energy from die sun because elec-tromagnetic energy travels through space.3 Many other kinds of energy are also types of electromagnetic energy.Radio,television,and radar signais travel from transmitters to receivers as low-energy electromagnetic waves. Infrared（红外线的）radiation is an electromagnetic wave.When it is absorbed by matter,heat is produced.Wayes of infrared and visible light have more energy than waves of radio,television,or radar. Ultraviolet rays（紫外线）and X-rays are eleetro-magnetic waves with even greater amounts of energy.Infrared radiation is used in cooking food and heating buildings.Sunlight and electric lights are part of our requirements for normal living. Ultraviolet radiation is useful in killing certain disease organisms.X-rays and gamma rays have so much energy that they travel right through solid objects.They can be used to detect and treat cancer。 X-rays are used in industry to find hiddencracks in metal,and in medicine to reveal broken bones.4 Usually we use electricity to generate electromagnetic energy.The source of most of our energy is the sun.Heat from the sun causes water to evaporate.When the water falls to the earth as rain,some of it is trapped behind dams and then used to operate electric generators,Other generators are powered by coal,but the energy stored in coal came from the sun,too.5 Until recently,the source of the tremendous amount of energy given off by the sun was a puzzle.If the sun depended on chemical reactions,it would have used up all its energy long ago.Experiments with electromagnetic radiation led to the theory that mass can be converted into energy．入bout forty years after the theory was proposed , nuclear energy was harnessed（利用）by man. Chemical energy comes from electron （电子）rearrangement. Nuclear energy comes from a change in the nucleus of an atom. Compared with chemi- cal reactions,nuclear reactions release millions of times more energy per pound of fuel.We now believe that the sun's energy comes from the nuclear reactions in which hydrogen is changed into helium（氦）.6 Nuclear energy is beginning to compete with coal as an economical source of power to generate elec- tricity.It is also being used to operate engines in large ships.Scientists continue to seek new and bettermethods of obtaining and using energy.Paragraph 4__________________A:Nuclear Reactions as the Lasting Source of the Sun's EnergyB:The Most Imoprtant Source of EnergyC:Types of Eleetromagnetie EnergyD:X-rays Are Used to Detect and Treat CancerE:Seeking New Sourees of EnergyF:Nuclear Energy Is Beginning to Compete With Coal
共用题干
Electromagnetic Energy
1 White light seems to be a combination of all colors.The energy that comes from a source of light is
not limited to the kind of energy you can see.Heat is given off by a flame or an electric light.On a cloudy
day it is possible to get a sunburn even though you feel cool.Visible light and the kind of energy that produce
warmth and sunburn are examples of electromagnetic energy.
2 The sun is 93 million miles away from the earth.Yct we can use energy from die sun because elec-
tromagnetic energy travels through space.
3 Many other kinds of energy are also types of electromagnetic energy.Radio,television,and radar signais
travel from transmitters to receivers as low-energy electromagnetic waves. Infrared（红外线的）radiation is an
electromagnetic wave.When it is absorbed by matter,heat is produced.Wayes of infrared and visible light
have more energy than waves of radio,television,or radar. Ultraviolet rays（紫外线）and X-rays are eleetro-
magnetic waves with even greater amounts of energy.Infrared radiation is used in cooking food and heating
buildings.Sunlight and electric lights are part of our requirements for normal living. Ultraviolet radiation is
useful in killing certain disease organisms.X-rays and gamma rays have so much energy that they travel right
through solid objects.They can be used to detect and treat cancer。 X-rays are used in industry to find hidden
cracks in metal,and in medicine to reveal broken bones.
4 Usually we use electricity to generate electromagnetic energy.The source of most of our energy is the
sun.Heat from the sun causes water to evaporate.When the water falls to the earth as rain,some of it is
trapped behind dams and then used to operate electric generators,Other generators are powered by coal,but
the energy stored in coal came from the sun,too.
5 Until recently,the source of the tremendous amount of energy given off by the sun was a puzzle.If
the sun depended on chemical reactions,it would have used up all its energy long ago.Experiments with
electromagnetic radiation led to the theory that mass can be converted into energy．入bout forty years after the
theory was proposed , nuclear energy was harnessed（利用）by man. Chemical energy comes from electron
（电子）rearrangement. Nuclear energy comes from a change in the nucleus of an atom. Compared with chemi-
cal reactions,nuclear reactions release millions of times more energy per pound of fuel.We now believe that
the sun's energy comes from the nuclear reactions in which hydrogen is changed into helium（氦）.
6 Nuclear energy is beginning to compete with coal as an economical source of power to generate elec-
tricity.It is also being used to operate engines in large ships.Scientists continue to seek new and better
methods of obtaining and using energy.
Electromagnetic Energy
1 White light seems to be a combination of all colors.The energy that comes from a source of light is
not limited to the kind of energy you can see.Heat is given off by a flame or an electric light.On a cloudy
day it is possible to get a sunburn even though you feel cool.Visible light and the kind of energy that produce
warmth and sunburn are examples of electromagnetic energy.
2 The sun is 93 million miles away from the earth.Yct we can use energy from die sun because elec-
tromagnetic energy travels through space.
3 Many other kinds of energy are also types of electromagnetic energy.Radio,television,and radar signais
travel from transmitters to receivers as low-energy electromagnetic waves. Infrared（红外线的）radiation is an
electromagnetic wave.When it is absorbed by matter,heat is produced.Wayes of infrared and visible light
have more energy than waves of radio,television,or radar. Ultraviolet rays（紫外线）and X-rays are eleetro-
magnetic waves with even greater amounts of energy.Infrared radiation is used in cooking food and heating
buildings.Sunlight and electric lights are part of our requirements for normal living. Ultraviolet radiation is
useful in killing certain disease organisms.X-rays and gamma rays have so much energy that they travel right
through solid objects.They can be used to detect and treat cancer。 X-rays are used in industry to find hidden
cracks in metal,and in medicine to reveal broken bones.
4 Usually we use electricity to generate electromagnetic energy.The source of most of our energy is the
sun.Heat from the sun causes water to evaporate.When the water falls to the earth as rain,some of it is
trapped behind dams and then used to operate electric generators,Other generators are powered by coal,but
the energy stored in coal came from the sun,too.
5 Until recently,the source of the tremendous amount of energy given off by the sun was a puzzle.If
the sun depended on chemical reactions,it would have used up all its energy long ago.Experiments with
electromagnetic radiation led to the theory that mass can be converted into energy．入bout forty years after the
theory was proposed , nuclear energy was harnessed（利用）by man. Chemical energy comes from electron
（电子）rearrangement. Nuclear energy comes from a change in the nucleus of an atom. Compared with chemi-
cal reactions,nuclear reactions release millions of times more energy per pound of fuel.We now believe that
the sun's energy comes from the nuclear reactions in which hydrogen is changed into helium（氦）.
6 Nuclear energy is beginning to compete with coal as an economical source of power to generate elec-
tricity.It is also being used to operate engines in large ships.Scientists continue to seek new and better
methods of obtaining and using energy.
Paragraph 4__________________
A:Nuclear Reactions as the Lasting Source of the Sun's Energy
B:The Most Imoprtant Source of Energy
C:Types of Eleetromagnetie Energy
D:X-rays Are Used to Detect and Treat Cancer
E:Seeking New Sourees of Energy
F:Nuclear Energy Is Beginning to Compete With Coal
A:Nuclear Reactions as the Lasting Source of the Sun's Energy
B:The Most Imoprtant Source of Energy
C:Types of Eleetromagnetie Energy
D:X-rays Are Used to Detect and Treat Cancer
E:Seeking New Sourees of Energy
F:Nuclear Energy Is Beginning to Compete With Coal
参考解析
解析：第三段的第一句为主题句，意为：许多其他种类的能量也是不同类型的电磁能。该段 列举了电磁能的具体例子，C项“Types of Electromagnetic Energy（电磁能的类型）”与主题句意 思吻合，故选C。
第四段的第二句为主题句，意为：我们的能量大多来白太阳。B项“The Most Important Source of Energy（最重要的能量来源）”与主题句意思吻合，故选B。
第五段的最后一句为主题句，意为；我们现在相信太阳的能量来自核反应，在此过程 中，氢转变为氦。A项“Nuclear Reactions as the Lasting Source of the Sun' s Energy（核反应是太 阳能最持久的来源）”与主题句意思吻合，故选A。
第六段的最后一句为主题句，意为：科学家仍在继续寻找获取和使用能量的新的、更好 的方法。E项“Seeking New Sources of Energy（寻找新的能源）”与主题句意思吻合，故选E。
第一段的最后一句指出，“可见光和其他能产生热量和造成晒伤的能量都是电磁能的 例子”。故选A。
第二段的第二句指出，“我们能使用太阳能，因为电磁能可以在太空中穿梭”。故选B。
第四段的最后一句指出，“其他的发电机靠煤炭驱动，但是，煤炭中储存的能量也来自 于太阳”。C项中的“came from the sun (来自太阳）”与原句意思相符，故选C。
第五段的第五句指出，化学能来自于电子重组。故选F。第4部分：阅读理解第一篇 本文介绍了引起食物中毒的原因及食物中毒的预防和治疗处理措施。
第四段的第二句为主题句，意为：我们的能量大多来白太阳。B项“The Most Important Source of Energy（最重要的能量来源）”与主题句意思吻合，故选B。
第五段的最后一句为主题句，意为；我们现在相信太阳的能量来自核反应，在此过程 中，氢转变为氦。A项“Nuclear Reactions as the Lasting Source of the Sun' s Energy（核反应是太 阳能最持久的来源）”与主题句意思吻合，故选A。
第六段的最后一句为主题句，意为：科学家仍在继续寻找获取和使用能量的新的、更好 的方法。E项“Seeking New Sources of Energy（寻找新的能源）”与主题句意思吻合，故选E。
第一段的最后一句指出，“可见光和其他能产生热量和造成晒伤的能量都是电磁能的 例子”。故选A。
第二段的第二句指出，“我们能使用太阳能，因为电磁能可以在太空中穿梭”。故选B。
第四段的最后一句指出，“其他的发电机靠煤炭驱动，但是，煤炭中储存的能量也来自 于太阳”。C项中的“came from the sun (来自太阳）”与原句意思相符，故选C。
第五段的第五句指出，化学能来自于电子重组。故选F。第4部分：阅读理解第一篇 本文介绍了引起食物中毒的原因及食物中毒的预防和治疗处理措施。
相关考题：
Electromagnetic EnergyWhite light seems to be a combination of all colors. The energy that comes from a source of light is not limited to the kind of energy you can see. Heat is given off by a flame or an electric light. On a cloudy day it is possible to get a sunburn even though you feel cool. Visible light and the kind of energy that produce warmth and sunburn are examples of electromagnetic energy.The sun is 93 million miles from the earth. Yet we can use energy from the sun because electromagnetic energy travels through space.Many other kinds of energy are also types of electromagnetic energy. Radio, television, and radar signals travel from transmitters to receivers as low-energy electromagnetic waves. Infrared (红外线的) radiation is an electromagnetic wave. When it is absorbed by matter, heat is produced. Waves of infrared and visible light have more energy than waves of radio, television, or radar. Ultraviolet rays (紫外线) and X-rays are electromagnetic waves with even greater amounts of energy. Infrared radiation is used in cooking food and heating buildings. Sunlight and electric lights are part of our requirements for normal living. Ultraviolet radiation is useful in killing certain disease organisms. X-rays and gamma rays have so mush energy that they travel right through solid objects. They can be used to detect and treat cancer. X-rays are used in industry to find hidden cracks in metal, and in medicine to reveal broken bones.Usually we use electricity to generate electromagnetic energy. The source of most of our energy is the sun. Heat from the sun causes water to evaporate. When the water falls to the earth as rain, some of it is trapped behind dams and then used to operate electric generators. Other generators are powered by coal, but the energy stored in coal came from the sun, too.Until recently, the source of the tremendous amount of energy given off by the sun was a puzzle. If the sun depended on chemical reactions, it would have used up all its energy long ago. Experiments with electromagnetic radiation led to the theory that mass can be converted into energy. About forty years after the theory was proposed, nuclear energy was harnessed (利用) by man. Chemical energy comes from electron (电子) rearrangement. Nuclear energy comes from a change in the nucleus of an atom. Compared with chemical reactions, nuclear reactions release millions of times more energy per pound of fuel. We now believe that the sun's energy comes from the nuclear reactions in which hydrogen is changed into helium(氦).Nuclear energy is beginning to compete with coal as an economical source of power to generate electricity. It is also being used to operate engines in large ships. Scientists continue to seek new and better methods of obtaining and using energy.A. Nuclear Reactions as the Lasting Source of the Sun's EnergyB. The Most Important Source of EnergyC. Types of Electromagnetic EnergyD. X-rays Are Used to Detect and Treat Cancer.E. Seeking New Sources of EnergyF. Nuclear Energy is Beginning to Compete with CoalParagraph 3 ______
共用题干Electromagnetic Energy1 White light seems to be a combination of all colors.The energy that comes from a source of light is not limited to the kind of energy you can see.Heat is given off by a flame or an electric light.On a cloudy day it is possible to get a sunburn even though you feel cool.Visible light and the kinds of energy that produce warmth and sunburn are examples of electromagnetic energy.2 The sun is 93 million miles from the earth.Yet we can use energy from the sun because electromagnetic energy travels through space.3 Many other kinds of energy are also types of electromagnetic energy.Radio,television,and radar signals travel from transmitters to receivers as low-energy electromagnetic waves.Infrared（红外线的）radiation is an electromagnetic wave.When it is absorbed by matter,heat is produced.Waves of infrared and visible light have more energy than waves of radio,television,or radar.Ultraviolet rays（紫外线）and X-rays are electromagnetic waves with even greater amounts of energy.Infrared radiation is used in cooking food and heating buildings. Sunlight and electric lights are part of our requirements for normal living.Ultraviolet radiation is useful in killing certain disease organisms.X-rays and gamma rays have so much energy that they travel through solid objects. They can be used to detect and treat cancer.X-rays are used in industry to find hidden cracks in metal,and in medicine to reveal broken bones.4 Usually we use electricity to generate electromagnetic energy.The source of most of our energy is the sun.Heat from the sun causes water to evaporate.When the water falls to the earth as rain,some of it is trapped behind dams and then used to operate electric generators.Other generators are powered by coal,but the energy stored in coal came from the sun,too.5 Until recently,the source of the tremendous amount of energy given off by the sun was a puzzle.If the sun depended on chemical reactions,it would have used up all its energy long ago.Experiments with electromagnetic radiation led to the theory that mass can be converted into energy.About forty years after the theory was proposed , nuclear energy was harnessed（利用）by man.Chemical energy comes from electron （电子）rearrangement.Nuclear energy comes from a change in the nucleus of an atom.Compared with chemical reactions,nuclear reactions release millions of times more energy per pound of fuel.We now believe that the sun's energy comes from the nuclear reactions in which hydrogen is changed into helium（氦）.6 Nuclear energy is beginning to compete with coal as an economical source of'power to generate electricity.It is also being used to operate engines in large ships.Scientists continue to seek new and better methods of obtaining and using energy.Infrared radiation can produce heat______. A:when it is absorbed by matterB:when it is cloudyC:because they can pass through solid objectsD:when the sunrays are fierce.E:when a change in the nucleus of an atom takes placeF:when electron rearrangement takes place
共用题干Electromagnetic Energy1 White light seems to be a combination of all colors.The energy that comes from a source of light is not limited to the kind of energy you can see.Heat is given off by a flame or an electric light.On a cloudyday it is possible to get a sunburn even though you feel cool.Visible light and the kind of energy that produce warmth and sunburn are examples of electromagnetic energy.2 The sun is 93 million miles away from the earth.Yet we can use energy from the sun because elec-tromagnetic energy travels through space.3 Many other kinds of energy are also types of electromagnetic energy.Radio,television,and radar signals travel from transmitters to receivers as low-energy electromagnetic waves. Infrared（红外线的）radiation is an electromagnetic wave.When it is absorbed by matter,heat is produced.Waves of infrared and visible light have more energy than waves of radio , television , or radar. Ultraviolet rays（紫外线）and X-rays are electro- magnetic waves with even greater amounts of energy.Infrared radiation is used in cooking food and heating buildings.Sunlight and electric lights are part of our requirements for normal living. Ultraviolet radiation is useful in killing certain disease organisms.X-rays and gamma rays have so much energy that they travel right through solid objects.They can be used to detect and treat cancer. X-rays are used in industry to find hidden cracks in metal,and in medicine to reveal broken bones.4 Usually we use electricity to generate electromagnetic energy.The source of most of our energy is the sun.Heat from the sun causes water to evaporate.When the water falls to the earth as rain,some of it is trapped behind dams and then used to operate electric generators.Other generators are powered by coal,but the energy stored in coal came from the sun,too.5 Until recently,the source of the tremendous amount of energy given off by the sun was a puzzle.If the.sun depended on chemical reactions,it would have used up all its energy long ago.Experiments with electromagnetic radiation led to the theory that mass can be converted into energy.About forty years after the theory was proposed , nuclear energy was harnessed（利用）by man. Chemical energy comes from electron （电子）rearrangement. Nuclear energy comes from a change in the nucleus of an atom. Compared with chemi-cal reactions,nuclear reactions release millions of times more energy per pound of fuel.We now believe that the sun's energy comes from the nuclear reactions in which hydrogen is changed into helium（氦）.6 Nuclear energy is beginning to compete with coal as an economical source of power to generate elec-tncity.It is also being used to operate engines in large ships.Scientists continue to seek new and better methods of obtaining and using energy.The energy stored in coal_____________.A:electromagnetic energyB:electromagnetic energy travels through spaceC:came from the sunD:when a change in the nucleus of an atom takes placeE:when the sunrays are fierceF:chemical energy is generated
共用题干Electromagnetic Energy1 White light seems to be a combination of all colors.The energy that comes from a source of light is not limited to the kind of energy you can see.Heat is given off by a flame or an electric light.On a cloudyday it is possible to get a sunburn even though you feel cool.Visible light and the kind of energy that produce warmth and sunburn are examples of electromagnetic energy.2 The sun is 93 million miles away from the earth.Yet we can use energy from the sun because elec-tromagnetic energy travels through space.3 Many other kinds of energy are also types of electromagnetic energy.Radio,television,and radar signals travel from transmitters to receivers as low-energy electromagnetic waves. Infrared（红外线的）radiation is an electromagnetic wave.When it is absorbed by matter,heat is produced.Waves of infrared and visible light have more energy than waves of radio , television , or radar. Ultraviolet rays（紫外线）and X-rays are electro- magnetic waves with even greater amounts of energy.Infrared radiation is used in cooking food and heating buildings.Sunlight and electric lights are part of our requirements for normal living. Ultraviolet radiation is useful in killing certain disease organisms.X-rays and gamma rays have so much energy that they travel right through solid objects.They can be used to detect and treat cancer. X-rays are used in industry to find hidden cracks in metal,and in medicine to reveal broken bones.4 Usually we use electricity to generate electromagnetic energy.The source of most of our energy is the sun.Heat from the sun causes water to evaporate.When the water falls to the earth as rain,some of it is trapped behind dams and then used to operate electric generators.Other generators are powered by coal,but the energy stored in coal came from the sun,too.5 Until recently,the source of the tremendous amount of energy given off by the sun was a puzzle.If the.sun depended on chemical reactions,it would have used up all its energy long ago.Experiments with electromagnetic radiation led to the theory that mass can be converted into energy.About forty years after the theory was proposed , nuclear energy was harnessed（利用）by man. Chemical energy comes from electron （电子）rearrangement. Nuclear energy comes from a change in the nucleus of an atom. Compared with chemi-cal reactions,nuclear reactions release millions of times more energy per pound of fuel.We now believe that the sun's energy comes from the nuclear reactions in which hydrogen is changed into helium（氦）.6 Nuclear energy is beginning to compete with coal as an economical source of power to generate elec-tncity.It is also being used to operate engines in large ships.Scientists continue to seek new and better methods of obtaining and using energy.When electron rearrangement takes place,_____________.A:electromagnetic energyB:electromagnetic energy travels through spaceC:came from the sunD:when a change in the nucleus of an atom takes placeE:when the sunrays are fierceF:chemical energy is generated
共用题干Electromagnetic Energy1 White light seems to be a combination of all colors.The energy that comes from a source of light is not limited to the kind of energy you can see.Heat is given off by a flame or an electric light.On a cloudyday it is possible to get a sunburn even though you feel cool.Visible light and the kind of energy that produce warmth and sunburn are examples of electromagnetic energy.2 The sun is 93 million miles away from the earth.Yet we can use energy from the sun because elec-tromagnetic energy travels through space.3 Many other kinds of energy are also types of electromagnetic energy.Radio,television,and radar signals travel from transmitters to receivers as low-energy electromagnetic waves. Infrared（红外线的）radiation is an electromagnetic wave.When it is absorbed by matter,heat is produced.Waves of infrared and visible light have more energy than waves of radio , television , or radar. Ultraviolet rays（紫外线）and X-rays are electro- magnetic waves with even greater amounts of energy.Infrared radiation is used in cooking food and heating buildings.Sunlight and electric lights are part of our requirements for normal living. Ultraviolet radiation is useful in killing certain disease organisms.X-rays and gamma rays have so much energy that they travel right through solid objects.They can be used to detect and treat cancer. X-rays are used in industry to find hidden cracks in metal,and in medicine to reveal broken bones.4 Usually we use electricity to generate electromagnetic energy.The source of most of our energy is the sun.Heat from the sun causes water to evaporate.When the water falls to the earth as rain,some of it is trapped behind dams and then used to operate electric generators.Other generators are powered by coal,but the energy stored in coal came from the sun,too.5 Until recently,the source of the tremendous amount of energy given off by the sun was a puzzle.If the.sun depended on chemical reactions,it would have used up all its energy long ago.Experiments with electromagnetic radiation led to the theory that mass can be converted into energy.About forty years after the theory was proposed , nuclear energy was harnessed（利用）by man. Chemical energy comes from electron （电子）rearrangement. Nuclear energy comes from a change in the nucleus of an atom. Compared with chemi-cal reactions,nuclear reactions release millions of times more energy per pound of fuel.We now believe that the sun's energy comes from the nuclear reactions in which hydrogen is changed into helium（氦）.6 Nuclear energy is beginning to compete with coal as an economical source of power to generate elec-tncity.It is also being used to operate engines in large ships.Scientists continue to seek new and better methods of obtaining and using energy.Paragraph 5_____________A:Nuclear Reactions as the Lasting Source of the Sun's EnergyB:The Most Important Source of EnergyC:Types of Electromagnetic EnergyD:X-rays Are Used to Detect and Treat CancerE:Seeking New Sources of EnergyF:Nuclear Energy Is Beginning to Compete With Coal
共用题干Electromagnetic Energy1 White light seems to be a combination of all colors.The energy that comes from a source of light is not limited to the kind of energy you can see.Heat is given off by a flame or an electric light.On a cloudy day it is possible to get a sunburn even though you feel cool.Visible light and the kinds of energy that produce warmth and sunburn are examples of electromagnetic energy.2 The sun is 93 million miles from the earth.Yet we can use energy from the sun because electromagnetic energy travels through space.3 Many other kinds of energy are also types of electromagnetic energy.Radio,television,and radar signals travel from transmitters to receivers as low-energy electromagnetic waves.Infrared（红外线的）radiation is an electromagnetic wave.When it is absorbed by matter,heat is produced.Waves of infrared and visible light have more energy than waves of radio,television,or radar.Ultraviolet rays（紫外线）and X-rays are electromagnetic waves with even greater amounts of energy.Infrared radiation is used in cooking food and heating buildings. Sunlight and electric lights are part of our requirements for normal living.Ultraviolet radiation is useful in killing certain disease organisms.X-rays and gamma rays have so much energy that they travel through solid objects. They can be used to detect and treat cancer.X-rays are used in industry to find hidden cracks in metal,and in medicine to reveal broken bones.4 Usually we use electricity to generate electromagnetic energy.The source of most of our energy is the sun.Heat from the sun causes water to evaporate.When the water falls to the earth as rain,some of it is trapped behind dams and then used to operate electric generators.Other generators are powered by coal,but the energy stored in coal came from the sun,too.5 Until recently,the source of the tremendous amount of energy given off by the sun was a puzzle.If the sun depended on chemical reactions,it would have used up all its energy long ago.Experiments with electromagnetic radiation led to the theory that mass can be converted into energy.About forty years after the theory was proposed , nuclear energy was harnessed（利用）by man.Chemical energy comes from electron （电子）rearrangement.Nuclear energy comes from a change in the nucleus of an atom.Compared with chemical reactions,nuclear reactions release millions of times more energy per pound of fuel.We now believe that the sun's energy comes from the nuclear reactions in which hydrogen is changed into helium（氦）.6 Nuclear energy is beginning to compete with coal as an economical source of'power to generate electricity.It is also being used to operate engines in large ships.Scientists continue to seek new and better methods of obtaining and using energy.Paragraph 4______A:Nuclear Reactions as the Lasting Source of the Sun's EnergyB:The Most Important Source of EnergyC:Types of Electromagnetic EnergyD:The Machines Used for Energy GenerationE:Seeking New Sources of EnergyF:The Use of Ultravio1et Radiation in Medicine
共用题干Electromagnetic Energy1 White light seems to be a combination of all colors.The energy that comes from a source of light is not limited to the kind of energy you can see.Heat is given off by a flame or an electric light.On a cloudy day it is possible to get a sunburn even though you feel cool.Visible light and the kinds of energy that produce warmth and sunburn are examples of electromagnetic energy.2 The sun is 93 million miles from the earth.Yet we can use energy from the sun because electromagnetic energy travels through space.3 Many other kinds of energy are also types of electromagnetic energy.Radio,television,and radar signals travel from transmitters to receivers as low-energy electromagnetic waves.Infrared（红外线的）radiation is an electromagnetic wave.When it is absorbed by matter,heat is produced.Waves of infrared and visible light have more energy than waves of radio,television,or radar.Ultraviolet rays（紫外线）and X-rays are electromagnetic waves with even greater amounts of energy.Infrared radiation is used in cooking food and heating buildings. Sunlight and electric lights are part of our requirements for normal living.Ultraviolet radiation is useful in killing certain disease organisms.X-rays and gamma rays have so much energy that they travel through solid objects. They can be used to detect and treat cancer.X-rays are used in industry to find hidden cracks in metal,and in medicine to reveal broken bones.4 Usually we use electricity to generate electromagnetic energy.The source of most of our energy is the sun.Heat from the sun causes water to evaporate.When the water falls to the earth as rain,some of it is trapped behind dams and then used to operate electric generators.Other generators are powered by coal,but the energy stored in coal came from the sun,too.5 Until recently,the source of the tremendous amount of energy given off by the sun was a puzzle.If the sun depended on chemical reactions,it would have used up all its energy long ago.Experiments with electromagnetic radiation led to the theory that mass can be converted into energy.About forty years after the theory was proposed , nuclear energy was harnessed（利用）by man.Chemical energy comes from electron （电子）rearrangement.Nuclear energy comes from a change in the nucleus of an atom.Compared with chemical reactions,nuclear reactions release millions of times more energy per pound of fuel.We now believe that the sun's energy comes from the nuclear reactions in which hydrogen is changed into helium（氦）.6 Nuclear energy is beginning to compete with coal as an economical source of'power to generate electricity.It is also being used to operate engines in large ships.Scientists continue to seek new and better methods of obtaining and using energy.X-rays and gamma rays can be used to detect and treat cancer______.A:when it is absorbed by matterB:when it is cloudyC:because they can pass through solid objectsD:when the sunrays are fierce.E:when a change in the nucleus of an atom takes placeF:when electron rearrangement takes place
共用题干Electromagnetic Energy1 White light seems to be a combination of all colors.The energy that comes from a source of light is not limited to the kind of energy you can see.Heat is given off by a flame or an electric light.On a cloudy day it is possible to get a sunburn even though you feel cool.Visible light and the kinds of energy that produce warmth and sunburn are examples of electromagnetic energy.2 The sun is 93 million miles from the earth.Yet we can use energy from the sun because electromagnetic energy travels through space.3 Many other kinds of energy are also types of electromagnetic energy.Radio,television,and radar signals travel from transmitters to receivers as low-energy electromagnetic waves.Infrared（红外线的）radiation is an electromagnetic wave.When it is absorbed by matter,heat is produced.Waves of infrared and visible light have more energy than waves of radio,television,or radar.Ultraviolet rays（紫外线）and X-rays are electromagnetic waves with even greater amounts of energy.Infrared radiation is used in cooking food and heating buildings. Sunlight and electric lights are part of our requirements for normal living.Ultraviolet radiation is useful in killing certain disease organisms.X-rays and gamma rays have so much energy that they travel through solid objects. They can be used to detect and treat cancer.X-rays are used in industry to find hidden cracks in metal,and in medicine to reveal broken bones.4 Usually we use electricity to generate electromagnetic energy.The source of most of our energy is the sun.Heat from the sun causes water to evaporate.When the water falls to the earth as rain,some of it is trapped behind dams and then used to operate electric generators.Other generators are powered by coal,but the energy stored in coal came from the sun,too.5 Until recently,the source of the tremendous amount of energy given off by the sun was a puzzle.If the sun depended on chemical reactions,it would have used up all its energy long ago.Experiments with electromagnetic radiation led to the theory that mass can be converted into energy.About forty years after the theory was proposed , nuclear energy was harnessed（利用）by man.Chemical energy comes from electron （电子）rearrangement.Nuclear energy comes from a change in the nucleus of an atom.Compared with chemical reactions,nuclear reactions release millions of times more energy per pound of fuel.We now believe that the sun's energy comes from the nuclear reactions in which hydrogen is changed into helium（氦）.6 Nuclear energy is beginning to compete with coal as an economical source of'power to generate electricity.It is also being used to operate engines in large ships.Scientists continue to seek new and better methods of obtaining and using energy.Chemical energy is generated______. A:when it is absorbed by matterB:when it is cloudyC:because they can pass through solid objectsD:when the sunrays are fierce.E:when a change in the nucleus of an atom takes placeF:when electron rearrangement takes place
共用题干Electromagnetic Energy1 White light seems to be a combination of all colors.The energy that comes from a source of light is not limited to the kind of energy you can see.Heat is given off by a flame or an electric light.On a cloudyday it is possible to get a sunburn even though you feel cool.Visible light and the kind of energy that produce warmth and sunburn are examples of electromagnetic energy.2 The sun is 93 million miles away from the earth.Yet we can use energy from the sun because elec-tromagnetic energy travels through space.3 Many other kinds of energy are also types of electromagnetic energy.Radio,television,and radar signals travel from transmitters to receivers as low-energy electromagnetic waves. Infrared（红外线的）radiation is an electromagnetic wave.When it is absorbed by matter,heat is produced.Waves of infrared and visible light have more energy than waves of radio , television , or radar. Ultraviolet rays（紫外线）and X-rays are electro- magnetic waves with even greater amounts of energy.Infrared radiation is used in cooking food and heating buildings.Sunlight and electric lights are part of our requirements for normal living. Ultraviolet radiation is useful in killing certain disease organisms.X-rays and gamma rays have so much energy that they travel right through solid objects.They can be used to detect and treat cancer. X-rays are used in industry to find hidden cracks in metal,and in medicine to reveal broken bones.4 Usually we use electricity to generate electromagnetic energy.The source of most of our energy is the sun.Heat from the sun causes water to evaporate.When the water falls to the earth as rain,some of it is trapped behind dams and then used to operate electric generators.Other generators are powered by coal,but the energy stored in coal came from the sun,too.5 Until recently,the source of the tremendous amount of energy given off by the sun was a puzzle.If the.sun depended on chemical reactions,it would have used up all its energy long ago.Experiments with electromagnetic radiation led to the theory that mass can be converted into energy.About forty years after the theory was proposed , nuclear energy was harnessed（利用）by man. Chemical energy comes from electron （电子）rearrangement. Nuclear energy comes from a change in the nucleus of an atom. Compared with chemi-cal reactions,nuclear reactions release millions of times more energy per pound of fuel.We now believe that the sun's energy comes from the nuclear reactions in which hydrogen is changed into helium（氦）.6 Nuclear energy is beginning to compete with coal as an economical source of power to generate elec-tncity.It is also being used to operate engines in large ships.Scientists continue to seek new and better methods of obtaining and using energy.Visible light that produces warmth is an example of______________.A:electromagnetic energyB:electromagnetic energy travels through spaceC:came from the sunD:when a change in the nucleus of an atom takes placeE:when the sunrays are fierceF:chemical energy is generated
共用题干Electromagnetic Energy1 White light seems to be a combination of all colors.The energy that comes from a source of light is not limited to the kind of energy you can see.Heat is given off by a flame or an electric light.On a cloudyday it is possible to get a sunburn even though you feel cool.Visible light and the kind of energy that produce warmth and sunburn are examples of electromagnetic energy.2 The sun is 93 million miles away from the earth.Yet we can use energy from the sun because elec-tromagnetic energy travels through space.3 Many other kinds of energy are also types of electromagnetic energy.Radio,television,and radar signals travel from transmitters to receivers as low-energy electromagnetic waves. Infrared（红外线的）radiation is an electromagnetic wave.When it is absorbed by matter,heat is produced.Waves of infrared and visible light have more energy than waves of radio , television , or radar. Ultraviolet rays（紫外线）and X-rays are electro- magnetic waves with even greater amounts of energy.Infrared radiation is used in cooking food and heating buildings.Sunlight and electric lights are part of our requirements for normal living. Ultraviolet radiation is useful in killing certain disease organisms.X-rays and gamma rays have so much energy that they travel right through solid objects.They can be used to detect and treat cancer. X-rays are used in industry to find hidden cracks in metal,and in medicine to reveal broken bones.4 Usually we use electricity to generate electromagnetic energy.The source of most of our energy is the sun.Heat from the sun causes water to evaporate.When the water falls to the earth as rain,some of it is trapped behind dams and then used to operate electric generators.Other generators are powered by coal,but the energy stored in coal came from the sun,too.5 Until recently,the source of the tremendous amount of energy given off by the sun was a puzzle.If the.sun depended on chemical reactions,it would have used up all its energy long ago.Experiments with electromagnetic radiation led to the theory that mass can be converted into energy.About forty years after the theory was proposed , nuclear energy was harnessed（利用）by man. Chemical energy comes from electron （电子）rearrangement. Nuclear energy comes from a change in the nucleus of an atom. Compared with chemi-cal reactions,nuclear reactions release millions of times more energy per pound of fuel.We now believe that the sun's energy comes from the nuclear reactions in which hydrogen is changed into helium（氦）.6 Nuclear energy is beginning to compete with coal as an economical source of power to generate elec-tncity.It is also being used to operate engines in large ships.Scientists continue to seek new and better methods of obtaining and using energy.We can use energy from the sun because_____________.A:electromagnetic energyB:electromagnetic energy travels through spaceC:came from the sunD:when a change in the nucleus of an atom takes placeE:when the sunrays are fierceF:chemical energy is generated
共用题干Energy CycleDo you find getting up in the morning so difficult that it's painful?This might be called laziness, but Dr. Kleitman has a new explanation.He has proved that everyone has a daily energy cycle.During the hours when you labor through your work you may say that you are"hot".That's true.The time of day when you feel most energetic is when your cycle of body temperature is at this peak.For some people the peak comes during the morning. For others it comes in the afternoon or evening. No one has discovered why this is so,but it leads to such familiar words as:"Get up, John!You'll be late for work again!"The possible explanation to the trouble is he is at his tempera-ture-and-energy peak in the evening. Much family quarrelling ends when husbands and wives realize what these energy cycles mean,and which cycle each member of the family has.You can't change your energy cycle,but you can learn to make your life fit it better. Habit can help,Dr. Kleitman believes.Maybe you're sleepy in the evening but feel you must stay up late anyway.Counteract your cycle to some extent by habitually staying up later than you want to.If your energy is low in the morning but you have an important job to do early in the day,rise before your usual hour. This won't change your cycle,but you'll get up steam and work better at your low point.Get off to a slow start,which saves your energy.Get up with a leisurely yawn and stretch.Sit on the edge of the bed a minute before putting your feet on the floor. Avoid the troublesome search for clean clothes by laying them out the night before.Whenever possible,do routine work in the afternoon and save tasks requiring more energy for your sharper hours.Energy cycle may be inherited from your parents.A:Right B:Wrong C:Not mentioned
共用题干Learn about Light1 .Ancient civilizations were amazed by the existence of light for thousands of years. The Greek philosophers believed that light was made up of countless,tiny particles that enter the human eye and create what we call vision. However,Empedocles and a Dutch scientist named Christian Huygens believed that light was like a wave. According to them,light spread out and travelled like a straight line. This theory was accepted during the 19th century.2 .In 1905,Albert Einstein published a research paper in which he explained what is re-ferred to as the photoelectric effect. This theory explains that particles make up light.The particles Einstein was referring to are weightless bundles（束）of electromagnetic（电磁）energy called photons（光子）.Today,scientists agree that light has a dual（二重）nature一it is part particle and part wave. It is a form of energy that allows us to see things around us.3 .Things that give off light are known as sources of light. During the day,the primary source of light is the sun. Other sources of light include stars,flames,flashlights,street lamps and glowing gases in glass tube.4 .When we draw the way light travels we always use straight lines. This is because nor-mally light rays travel in a straight line. However,there are some instances that can change the path and even the nature of light. They are reflection,absorption,interference（干扰）, etc.5 .Physicists have attempted to measure the speed of light since the early times. In 1849, Hippolyte Fizeau conducted an experiment by directing a beam of light to a mirror located kilometers away and placed a rotating cogwheel（旋转齿轮）between the beam and the mirror. From the rate of rotation of the wheel,number of wheel's teeth and distance of the mirror,he was able to calculate that the speed of light is 313 million meters per second. In a vacuum（真空）,however,the speed of light is 299,792,458 meters per second. This is about a million times faster than the speed of an airplane.Hippolyte Fizeau conducted an experiment to measure______.A: sources of lightB: the speed of lightC: the path of lightD: a straight lineE: a beam of lightF: a form of energy
共用题干Learn about Light1 .Ancient civilizations were amazed by the existence of light for thousands of years. The Greek philosophers believed that light was made up of countless,tiny particles that enter the human eye and create what we call vision. However,Empedocles and a Dutch scientist named Christian Huygens believed that light was like a wave. According to them,light spread out and travelled like a straight line. This theory was accepted during the 19th century.2 .In 1905,Albert Einstein published a research paper in which he explained what is re-ferred to as the photoelectric effect. This theory explains that particles make up light.The particles Einstein was referring to are weightless bundles（束）of electromagnetic（电磁）energy called photons（光子）.Today,scientists agree that light has a dual（二重）nature一it is part particle and part wave. It is a form of energy that allows us to see things around us.3 .Things that give off light are known as sources of light. During the day,the primary source of light is the sun. Other sources of light include stars,flames,flashlights,street lamps and glowing gases in glass tube.4 .When we draw the way light travels we always use straight lines. This is because nor-mally light rays travel in a straight line. However,there are some instances that can change the path and even the nature of light. They are reflection,absorption,interference（干扰）, etc.5 .Physicists have attempted to measure the speed of light since the early times. In 1849, Hippolyte Fizeau conducted an experiment by directing a beam of light to a mirror located kilometers away and placed a rotating cogwheel（旋转齿轮）between the beam and the mirror. From the rate of rotation of the wheel,number of wheel's teeth and distance of the mirror,he was able to calculate that the speed of light is 313 million meters per second. In a vacuum（真空）,however,the speed of light is 299,792,458 meters per second. This is about a million times faster than the speed of an airplane.Objects are visible to the human eye as light is______.A: sources of lightB: the speed of lightC: the path of lightD: a straight lineE: a beam of lightF: a form of energy
共用题干Learn about Light1 .Ancient civilizations were amazed by the existence of light for thousands of years. The Greek philosophers believed that light was made up of countless,tiny particles that enter the human eye and create what we call vision. However,Empedocles and a Dutch scientist named Christian Huygens believed that light was like a wave. According to them,light spread out and travelled like a straight line. This theory was accepted during the 19th century.2 .In 1905,Albert Einstein published a research paper in which he explained what is re-ferred to as the photoelectric effect. This theory explains that particles make up light.The particles Einstein was referring to are weightless bundles（束）of electromagnetic（电磁）energy called photons（光子）.Today,scientists agree that light has a dual（二重）nature一it is part particle and part wave. It is a form of energy that allows us to see things around us.3 .Things that give off light are known as sources of light. During the day,the primary source of light is the sun. Other sources of light include stars,flames,flashlights,street lamps and glowing gases in glass tube.4 .When we draw the way light travels we always use straight lines. This is because nor-mally light rays travel in a straight line. However,there are some instances that can change the path and even the nature of light. They are reflection,absorption,interference（干扰）, etc.5 .Physicists have attempted to measure the speed of light since the early times. In 1849, Hippolyte Fizeau conducted an experiment by directing a beam of light to a mirror located kilometers away and placed a rotating cogwheel（旋转齿轮）between the beam and the mirror. From the rate of rotation of the wheel,number of wheel's teeth and distance of the mirror,he was able to calculate that the speed of light is 313 million meters per second. In a vacuum（真空）,however,the speed of light is 299,792,458 meters per second. This is about a million times faster than the speed of an airplane.Some instances such as reflection and absorption can change______.A: sources of lightB: the speed of lightC: the path of lightD: a straight lineE: a beam of lightF: a form of energy
共用题干Electromagnetic Energy1 White light seems to be a combination of all colors.The energy that comes from a source of light isnot limited to the kind of energy you can see.Heat is given off by a flame or an electric light.On a cloudy day it is possible to get a sunburn even though you feel cool.Visible light and the kind of energy that produce warmth and sunburn are examples of electromagnetic energy.2 The sun is 93 million miles away from the earth.Yct we can use energy from die sun because elec-tromagnetic energy travels through space.3 Many other kinds of energy are also types of electromagnetic energy.Radio,television,and radar signais travel from transmitters to receivers as low-energy electromagnetic waves. Infrared（红外线的）radiation is an electromagnetic wave.When it is absorbed by matter,heat is produced.Wayes of infrared and visible light have more energy than waves of radio,television,or radar. Ultraviolet rays（紫外线）and X-rays are eleetro-magnetic waves with even greater amounts of energy.Infrared radiation is used in cooking food and heating buildings.Sunlight and electric lights are part of our requirements for normal living. Ultraviolet radiation is useful in killing certain disease organisms.X-rays and gamma rays have so much energy that they travel right through solid objects.They can be used to detect and treat cancer。 X-rays are used in industry to find hiddencracks in metal,and in medicine to reveal broken bones.4 Usually we use electricity to generate electromagnetic energy.The source of most of our energy is the sun.Heat from the sun causes water to evaporate.When the water falls to the earth as rain,some of it is trapped behind dams and then used to operate electric generators,Other generators are powered by coal,but the energy stored in coal came from the sun,too.5 Until recently,the source of the tremendous amount of energy given off by the sun was a puzzle.If the sun depended on chemical reactions,it would have used up all its energy long ago.Experiments with electromagnetic radiation led to the theory that mass can be converted into energy．入bout forty years after the theory was proposed , nuclear energy was harnessed（利用）by man. Chemical energy comes from electron （电子）rearrangement. Nuclear energy comes from a change in the nucleus of an atom. Compared with chemi- cal reactions,nuclear reactions release millions of times more energy per pound of fuel.We now believe that the sun's energy comes from the nuclear reactions in which hydrogen is changed into helium（氦）.6 Nuclear energy is beginning to compete with coal as an economical source of power to generate elec- tricity.It is also being used to operate engines in large ships.Scientists continue to seek new and bettermethods of obtaining and using energy.We can use energy from the sun because_______________.A:electromagnetic energyB:electromagnetic energy travels through spaceC:came from the sunD:when a change in the nucleus of an atom takes placeE:whlen the sunrays are fierce F:chemical energy is generated
共用题干Energy CycleDo you find getting up in the morning so difficult that it's painful?This might be called laziness,but Dr. Kleitman has a new explanation. He has proved that everyone has a daily energy cycle.During the hours when you labor through your work you may say that you're“hot”.That's true .The time of day when you feel most energetic is when your cycle of body temperature is at its peak .For some people the peak comes during the morning. For others it comes in the afternoon or evening.No one has discovered why this is so,but it leads to such familiar monologues as:“Get up,John!You'll be late for work again!”The possible explanation to the trouble is that John is at his temperature-and-energy peak in the evening. Much family quarrelling ends when husbands and wives realize what these energy cycles mean,and which cycle each member of the family has.You can't change your energy cycle,but you can learn to make your life fit to it better. Habit can help,Dr. Kleitman believes. Maybe you're sleepy in the evening but you must stay up late anyway .Counteract your cycle to some extent by habitually staying up later than you want to. If your energy is low in the morning but you have an important job to do early in the day,rise before your usual hour. This won't change your cycle,but you'll get up steam and work better at your low point.Get off to a slow start which saves your energy .Get up with a leisurely yawn and stretch.Sit on the edge of the bed a minute before putting your feet on the floor. Avoid the trouble of searching for clean clothes by laying them out the night before .Whenever possible,do routine work in the afternoon and save tasks requiring more energy or concentration for your sharper hours. Which of the following statements is NOT TRUE?A: Getting off to work with a minimum effort helps save one's energy.B: Dr. Kleitman explains why people reach their peak at different hours of day.C: Habit helps a person adapt to his own energy cycle.D: Children have energy cycles,too.
共用题干Electromagnetic Energy1 White light seems to be a combination of all colors.The energy that comes from a source of light isnot limited to the kind of energy you can see.Heat is given off by a flame or an electric light.On a cloudy day it is possible to get a sunburn even though you feel cool.Visible light and the kind of energy that produce warmth and sunburn are examples of electromagnetic energy.2 The sun is 93 million miles away from the earth.Yct we can use energy from die sun because elec-tromagnetic energy travels through space.3 Many other kinds of energy are also types of electromagnetic energy.Radio,television,and radar signais travel from transmitters to receivers as low-energy electromagnetic waves. Infrared（红外线的）radiation is an electromagnetic wave.When it is absorbed by matter,heat is produced.Wayes of infrared and visible light have more energy than waves of radio,television,or radar. Ultraviolet rays（紫外线）and X-rays are eleetro-magnetic waves with even greater amounts of energy.Infrared radiation is used in cooking food and heating buildings.Sunlight and electric lights are part of our requirements for normal living. Ultraviolet radiation is useful in killing certain disease organisms.X-rays and gamma rays have so much energy that they travel right through solid objects.They can be used to detect and treat cancer。 X-rays are used in industry to find hiddencracks in metal,and in medicine to reveal broken bones.4 Usually we use electricity to generate electromagnetic energy.The source of most of our energy is the sun.Heat from the sun causes water to evaporate.When the water falls to the earth as rain,some of it is trapped behind dams and then used to operate electric generators,Other generators are powered by coal,but the energy stored in coal came from the sun,too.5 Until recently,the source of the tremendous amount of energy given off by the sun was a puzzle.If the sun depended on chemical reactions,it would have used up all its energy long ago.Experiments with electromagnetic radiation led to the theory that mass can be converted into energy．入bout forty years after the theory was proposed , nuclear energy was harnessed（利用）by man. Chemical energy comes from electron （电子）rearrangement. Nuclear energy comes from a change in the nucleus of an atom. Compared with chemi- cal reactions,nuclear reactions release millions of times more energy per pound of fuel.We now believe that the sun's energy comes from the nuclear reactions in which hydrogen is changed into helium（氦）.6 Nuclear energy is beginning to compete with coal as an economical source of power to generate elec- tricity.It is also being used to operate engines in large ships.Scientists continue to seek new and bettermethods of obtaining and using energy.The energy stored in coal_______________.A:electromagnetic energyB:electromagnetic energy travels through spaceC:came from the sunD:when a change in the nucleus of an atom takes placeE:whlen the sunrays are fierce F:chemical energy is generated
共用题干Electromagnetic Energy1 White light seems to be a combination of all colors.The energy that comes from a source of light isnot limited to the kind of energy you can see.Heat is given off by a flame or an electric light.On a cloudy day it is possible to get a sunburn even though you feel cool.Visible light and the kind of energy that produce warmth and sunburn are examples of electromagnetic energy.2 The sun is 93 million miles away from the earth.Yct we can use energy from die sun because elec-tromagnetic energy travels through space.3 Many other kinds of energy are also types of electromagnetic energy.Radio,television,and radar signais travel from transmitters to receivers as low-energy electromagnetic waves. Infrared（红外线的）radiation is an electromagnetic wave.When it is absorbed by matter,heat is produced.Wayes of infrared and visible light have more energy than waves of radio,television,or radar. Ultraviolet rays（紫外线）and X-rays are eleetro-magnetic waves with even greater amounts of energy.Infrared radiation is used in cooking food and heating buildings.Sunlight and electric lights are part of our requirements for normal living. Ultraviolet radiation is useful in killing certain disease organisms.X-rays and gamma rays have so much energy that they travel right through solid objects.They can be used to detect and treat cancer。 X-rays are used in industry to find hiddencracks in metal,and in medicine to reveal broken bones.4 Usually we use electricity to generate electromagnetic energy.The source of most of our energy is the sun.Heat from the sun causes water to evaporate.When the water falls to the earth as rain,some of it is trapped behind dams and then used to operate electric generators,Other generators are powered by coal,but the energy stored in coal came from the sun,too.5 Until recently,the source of the tremendous amount of energy given off by the sun was a puzzle.If the sun depended on chemical reactions,it would have used up all its energy long ago.Experiments with electromagnetic radiation led to the theory that mass can be converted into energy．入bout forty years after the theory was proposed , nuclear energy was harnessed（利用）by man. Chemical energy comes from electron （电子）rearrangement. Nuclear energy comes from a change in the nucleus of an atom. Compared with chemi- cal reactions,nuclear reactions release millions of times more energy per pound of fuel.We now believe that the sun's energy comes from the nuclear reactions in which hydrogen is changed into helium（氦）.6 Nuclear energy is beginning to compete with coal as an economical source of power to generate elec- tricity.It is also being used to operate engines in large ships.Scientists continue to seek new and bettermethods of obtaining and using energy.When electron rearrangement takes place_______________.A:electromagnetic energyB:electromagnetic energy travels through spaceC:came from the sunD:when a change in the nucleus of an atom takes placeE:whlen the sunrays are fierce F:chemical energy is generated
共用题干Electromagnetic Energy1 White light seems to be a combination of all colors.The energy that comes from a source of light isnot limited to the kind of energy you can see.Heat is given off by a flame or an electric light.On a cloudy day it is possible to get a sunburn even though you feel cool.Visible light and the kind of energy that produce warmth and sunburn are examples of electromagnetic energy.2 The sun is 93 million miles away from the earth.Yct we can use energy from die sun because elec-tromagnetic energy travels through space.3 Many other kinds of energy are also types of electromagnetic energy.Radio,television,and radar signais travel from transmitters to receivers as low-energy electromagnetic waves. Infrared（红外线的）radiation is an electromagnetic wave.When it is absorbed by matter,heat is produced.Wayes of infrared and visible light have more energy than waves of radio,television,or radar. Ultraviolet rays（紫外线）and X-rays are eleetro-magnetic waves with even greater amounts of energy.Infrared radiation is used in cooking food and heating buildings.Sunlight and electric lights are part of our requirements for normal living. Ultraviolet radiation is useful in killing certain disease organisms.X-rays and gamma rays have so much energy that they travel right through solid objects.They can be used to detect and treat cancer。 X-rays are used in industry to find hiddencracks in metal,and in medicine to reveal broken bones.4 Usually we use electricity to generate electromagnetic energy.The source of most of our energy is the sun.Heat from the sun causes water to evaporate.When the water falls to the earth as rain,some of it is trapped behind dams and then used to operate electric generators,Other generators are powered by coal,but the energy stored in coal came from the sun,too.5 Until recently,the source of the tremendous amount of energy given off by the sun was a puzzle.If the sun depended on chemical reactions,it would have used up all its energy long ago.Experiments with electromagnetic radiation led to the theory that mass can be converted into energy．入bout forty years after the theory was proposed , nuclear energy was harnessed（利用）by man. Chemical energy comes from electron （电子）rearrangement. Nuclear energy comes from a change in the nucleus of an atom. Compared with chemi- cal reactions,nuclear reactions release millions of times more energy per pound of fuel.We now believe that the sun's energy comes from the nuclear reactions in which hydrogen is changed into helium（氦）.6 Nuclear energy is beginning to compete with coal as an economical source of power to generate elec- tricity.It is also being used to operate engines in large ships.Scientists continue to seek new and bettermethods of obtaining and using energy.Visible light that produces warmth is an example of _______________.A:electromagnetic energyB:electromagnetic energy travels through spaceC:came from the sunD:when a change in the nucleus of an atom takes placeE:whlen the sunrays are fierce F:chemical energy is generated
共用题干Learn About Light1 Ancient civilizations were amazed by the existence of light for thousands of years?The Greek philoso- phrrs believed that light was made up of countless,tiny particles that enter the human eye and create what we call vision.However,Empedocles and a Dutch scientist named Christian Huygens believed that light wag like a wave.According to them,light spread out and travelled like a straight line.This theory was acceptedduring the 19th century.2 In 1905,Albert Einstein published a research paper in which he explained what is referred to as the photoelectric effect.This theory explains that particles make up light.The particles Einstein was referring to are weightless bundles（束）of electromagnetic（电磁）energy called photons（光子）.Today,scientists agree that light has a dual（二重）nature一it is part particle and part wave. It is a form of energy that allows us tosee things around us.3 Things that give off light are known as sources of light.During the day,the primary source of light is the sun.Other sources of light include stars,flames,flashllights,street lamps and glowing gases in glass tube.4 When we draw the way light travels we always use straight lines.This is because normally light rays travel in a straight line.However,there are some instances that can change the path and even the nature of light. They are reflection,absorption,interference（干扰）,etc.5 Physicists have attempted to measure the speed of light since the early times.In 1849,Hippolyte Fizeau conducted an experiment by directing a beam of light to a mirror located kilometers away and placed a rotating cogwheel（旋转齿轮）between the beam and the mirror. From the rate of rotation of the wheel, number of wheel'S teeth and distance of the mirror,he was able to calculate that the speed of light is 313 million meters per second.In a vacuum（真空）,however,the speed of light is 299,792,458 meters per second.This is about a million times faster than the speed of an airplane.Objects are visible to the human eye as light is_______. A:sources of lightB:the speed of light C:the path of lightD:a straight lineE:a beam of lightF:a form of energy
共用题干Energy CycleDo you find getting up in the morning so difficult that it's painful?This might be called laziness,but Dr. Kleitman has a new explanation. He has proved that everyone has a daily energy cycle.During the hours when you labor through your work you may say that you're“hot”.That's true .The time of day when you feel most energetic is when your cycle of body temperature is at its peak .For some people the peak comes during the morning. For others it comes in the afternoon or evening.No one has discovered why this is so,but it leads to such familiar monologues as:“Get up,John!You'll be late for work again!”The possible explanation to the trouble is that John is at his temperature-and-energy peak in the evening. Much family quarrelling ends when husbands and wives realize what these energy cycles mean,and which cycle each member of the family has.You can't change your energy cycle,but you can learn to make your life fit to it better. Habit can help,Dr. Kleitman believes. Maybe you're sleepy in the evening but you must stay up late anyway .Counteract your cycle to some extent by habitually staying up later than you want to. If your energy is low in the morning but you have an important job to do early in the day,rise before your usual hour. This won't change your cycle,but you'll get up steam and work better at your low point.Get off to a slow start which saves your energy .Get up with a leisurely yawn and stretch.Sit on the edge of the bed a minute before putting your feet on the floor. Avoid the trouble of searching for clean clothes by laying them out the night before .Whenever possible,do routine work in the afternoon and save tasks requiring more energy or concentration for your sharper hours. You are advised to rise with a yawn and stretch because it will_______.A: help to keep your energy for the day's workB: help you to control your temper early in the dayC: enable you to concentrate on your routine workD: keep your energy cycle under control all day
共用题干Learn About Light1 Ancient civilizations were amazed by the existence of light for thousands of years?The Greek philoso- phrrs believed that light was made up of countless,tiny particles that enter the human eye and create what we call vision.However,Empedocles and a Dutch scientist named Christian Huygens believed that light wag like a wave.According to them,light spread out and travelled like a straight line.This theory was acceptedduring the 19th century.2 In 1905,Albert Einstein published a research paper in which he explained what is referred to as the photoelectric effect.This theory explains that particles make up light.The particles Einstein was referring to are weightless bundles（束）of electromagnetic（电磁）energy called photons（光子）.Today,scientists agree that light has a dual（二重）nature一it is part particle and part wave. It is a form of energy that allows us tosee things around us.3 Things that give off light are known as sources of light.During the day,the primary source of light is the sun.Other sources of light include stars,flames,flashllights,street lamps and glowing gases in glass tube.4 When we draw the way light travels we always use straight lines.This is because normally light rays travel in a straight line.However,there are some instances that can change the path and even the nature of light. They are reflection,absorption,interference（干扰）,etc.5 Physicists have attempted to measure the speed of light since the early times.In 1849,Hippolyte Fizeau conducted an experiment by directing a beam of light to a mirror located kilometers away and placed a rotating cogwheel（旋转齿轮）between the beam and the mirror. From the rate of rotation of the wheel, number of wheel'S teeth and distance of the mirror,he was able to calculate that the speed of light is 313 million meters per second.In a vacuum（真空）,however,the speed of light is 299,792,458 meters per second.This is about a million times faster than the speed of an airplane.Some instances such as reflection and absorption can change_________. A:sources of lightB:the speed of light C:the path of lightD:a straight lineE:a beam of lightF:a form of energy
共用题干第三篇Weaving with LightIn the Sierra Madre mountain range of west central Mexico,the native Huichol people live much the way their ancestors did一without electricity,That’s because it's too expensive to string power lines to the remote mountain areas where they live.To help support themselves,the Huichol create beautiful artwork. They sell their art in cities hundreds of miles away from their villages.And without electricity一at home or on the road,they can only work during daylight hours?When it gets dark,they must stop whatever they'redoing.Now，a team of scientists,designers,and architects is using new technologies to provide the Huichol with light after the sun sets.The scientists'technique involves weaving tiny electronic crystals into fabrics that can be made into clothes,bags,or other items.By collecting the sun’s energy during the day,these lightweight fabrics provide bright white light atnight一 Their inventors have named the fabrics" Portable（轻便的）Lights."Portable Lights have the potential to transform the lives of people without electricity around the world.At the core of Portable Lights technology are devices called high-brightness light-emitting diodes（高亮 度发光二极管）,or HB LEDs. These tiny lights appear in digital clocks, televisions, and streetlights.LEDs are completely different from the light bulbs（灯泡）.Most of those glass bulbs belong to a type called incandescent lights（白炽灯）.Inside, electricity heats a metal coil（线圈）to about 2. 200 degrees Celsius.At that temperature,bulbs give off light we can see.Ninety percent of energy produced by mnean- descent lights,however,is heat一and invisible.With all that wasted energy,bulbs burn out quickly. Theyare also easily broken.LEDs,on the other hand,are like tiny pieces of rock made up of molecules（分子）that are arranged in a crystal structure.When an electric current passes through a LED,the crystal structure produces light. Un- like incandescent bulbs,they can produce light of various colors.Within a LED,the type of molecules and their particular arrangement determine what color is produced.All of the following are disadvantages of incandescent lights EXCEPT that__________.A:they are not bright enough B:they burn out quicklyC:they are easily brokenD:they waste most of the energy produced
If you are writing or studying,it makes very much difference where the light comes from.People who use books and pens every day have to be especially careful about the way the light shines on their work.Every house gets its light either from daylight through the windows--which is the best to use--or from lamps or electricity;but whichever kind of light it is,the way it shines toward our book or work is a matter of great importance to the eyes.Take a book,sit with your back toward the window,and try to read.Your shadow（影子）falls all over the page and makes it almost as bad for your eyes as if you were in a dark room.Now turnaround and face the window.The page is in the shadow again,while the bright light is in your eyes.Try sitting with your right side toward the window.This is very well for reading,but if you were writing,the shadow of your hand would fall across the page and bother（打搅）you a little.There is just one other way:sit with your left side to the window.Now everything is perfect for reading and for writing,too.Whatever kind of light is in the room,the rule about the right to sit is always the same.Which of the following is true?A.How the light shines on our work is of much importance.B.The way the light shines on your work makes no difference.C.We needn't care about where the light comes from.D.People can write or study under a light that comes from any direction.
单选题What is the lifesaving signal for You are seen -assistance will be given as soon as possible?（）A3 white star signalsBHorizontal motion with a white flagCVertical motion of a white lightDCode letter K by blinker light
单选题The lifesaving signal indicating You are seen - assistance will be given as soon as possible is the（）.Avertical motion of white flagsBvertical motion of a white light or flareCfiring of a green star signalDNone of the above