If the population of the earth goes on increasing at its present rate, there will eventually not be enough resources left to sustain life on the planet.By the middle of the 21st century,if present trends continue, we will have used up all the oil that drives our cars,for example.Even if scientists develop new ways of feeding the human race,the crowded conditions on earth will make it necessary for lus to look for open space somewhere else. But none of the other planets in our solar system are capable of supporting life at present. One possible solution to the problem, however,has recently been suggested by American scientist, Professor Carl Sagan.Sagan believes that before the earth's resources are compleetely exhausted it will be possible to change the atmophere of Venus and so create a new world almost as large as earth itself. The difficult is that Venus is much hotter than the earth and there is only a tiny amount of water there.Sagan proposes that algae organisms that can live in extremely hot or cold atmospheres and at the same time produce oxygen,should be bred in condition similar to those on Venus.As soon as this has been done, the algae will be placed in small rockets. Spaceship will then fly to Venus and fire the rockets into the atmosphere .In a fairly short time, the alge will break down the carbon dioxide into oxygen and carbon.When the algae have done theri work, the atmosphere will become cooler,but befor man can set foot on Venus it will be neccessary for the oxygen to produce rain. The surface of the planet will still be too hot for man to land on it but the rain will eventually fall and in a few years something like earth will be reproduced on Venus.On Venus there is a lot of ________.a.water b.carbon dioxidec.carbon monoxided.oxygen
If the population of the earth goes on increasing at its present rate, there will eventually not be enough resources left to sustain life on the planet.By the middle of the 21st century,if present trends continue, we will have used up all the oil that drives our cars,for example.Even if scientists develop new ways of feeding the human race,the crowded conditions on earth will make it necessary for lus to look for open space somewhere else. But none of the other planets in our solar system are capable of supporting life at present. One possible solution to the problem, however,has recently been suggested by American scientist, Professor Carl Sagan.
Sagan believes that before the earth's resources are compleetely exhausted it will be possible to change the atmophere of Venus and so create a new world almost as large as earth itself. The difficult is that Venus is much hotter than the earth and there is only a tiny amount of water there.
Sagan proposes that algae organisms that can live in extremely hot or cold atmospheres and at the same time produce oxygen,should be bred in condition similar to those on Venus.As soon as this has been done, the algae will be placed in small rockets. Spaceship will then fly to Venus and fire the rockets into the atmosphere .In a fairly short time, the alge will break down the carbon dioxide into oxygen and carbon.
When the algae have done theri work, the atmosphere will become cooler,but befor man can set foot on Venus it will be neccessary for the oxygen to produce rain. The surface of the planet will still be too hot for man to land on it but the rain will eventually fall and in a few years something like earth will be reproduced on Venus.
On Venus there is a lot of ________.
Sagan believes that before the earth's resources are compleetely exhausted it will be possible to change the atmophere of Venus and so create a new world almost as large as earth itself. The difficult is that Venus is much hotter than the earth and there is only a tiny amount of water there.
Sagan proposes that algae organisms that can live in extremely hot or cold atmospheres and at the same time produce oxygen,should be bred in condition similar to those on Venus.As soon as this has been done, the algae will be placed in small rockets. Spaceship will then fly to Venus and fire the rockets into the atmosphere .In a fairly short time, the alge will break down the carbon dioxide into oxygen and carbon.
When the algae have done theri work, the atmosphere will become cooler,but befor man can set foot on Venus it will be neccessary for the oxygen to produce rain. The surface of the planet will still be too hot for man to land on it but the rain will eventually fall and in a few years something like earth will be reproduced on Venus.
On Venus there is a lot of ________.
a.water
b.carbon dioxide
c.carbon monoxide
d.oxygen
b.carbon dioxide
c.carbon monoxide
d.oxygen
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完形填空Many of the world’s pollution problems have been caused by the crowding of large groups of people into cities.Satisfying the 21 of the people leads to further polluting by industry.If the rapid increase in human population 22 at the present rate (比率), there may be much greater harm.Some scientists speak of the 23 in number of people as “Population Pollution”.About 2000 years ago, the world 24 was probably about 250 million.It reached a billion in 1850.By 1930 the population was two billion.It is 25 three and a half billion.It is expected to double by the year 2000.If the population continues to grow at the same 26 , there would be 25 billion people in the world a hundred years from now.Man has been using the earth’s 27 more and more rapidly over the years.Some of them are almost gone.Now many people believe that man’s greatest 28 is how to control the growth of this population.The materials in the world will not support the human population in time to come if the present rate of increase continues.29 there is over crowding in the cities and hunger in some countries.Can man’s rate of increase continue?Many people believe that human survival (幸存者) in the future 30 on the answer to the question.21.A.needsB.suppliesC.serviceD.supports22.A.stopsB.continuesC.slows downD.adds to23.A.increaseB.reduceC.countryD.improvement24.A.peopleB.situationC.populationD.land25.A.nowB.in the pastC.in the futureD.then26.A.placeB.timeC.rateD.result27.A coalB.oilC.minesD.resources28.A.problemB.powerC.planD.idea29.A.AlreadyB.YetC.StillD.Often30.A.feedsB.livesC.keepsD.depends
Population experts tell us that by the year 2025, the population in cities in developing nations will increase to five times its present size.()
Continuity of life refers to whether an entity continues to operate or technically dissolves and ceases to exist in its present form. when a change occurs in the ownership structure.() 此题为判断题(对，错)。
Which of the following statements is NOT true?A) World population is increasing at a rate of 150 per minute.B) Lower death rates also contribute to world population growth.C) The population of Columbia has been doubling every year for 21 years.D) The United States is usually doubling its population about every 87 years.
These natural resources will be______sooner or later if the present rate of exploitation continues.A．depletedB．deployedC．inclinedD．mingled
By the middle of the 21st century，the vast majority of the world‘s population will be living in cities _______ in the country. A. other than B. more than C. better than D. rather than
Passage 2If the population of the earth goes on increasing at its present rate, there will eventually not be enough resources left to sustain life on the planet. By the middle of the 21st century, if present trends continue, we will have used up all the oil that drives our cars, for example. Even if scientists develop new ways of feeding the human race, the crowded conditions on earth will make it necessary for us to look for open space somewhere else. But none of the other planets in our solar system are capable of supporting life at present. One possible solution to the problem, however, has recently been suggested by an American scientist, Professor Carl Sagan.Sagan believes that before the earth's resources are completely exhausted it will be possible to change the atmosphere of Venus and so create a new world almost as large as earth itself. The difficulty is that Venus is much hotter than the earth and there is only a tiny amount of water there.Sagan proposes that algae organisms, which can live in extremely hot or cold atmospheres and at the same time produce oxygen, should be bred in conditions similar to those on Venus. As soon as this has been done, the algae will be placed in small rockets. Spaceships will then fly to Venus and fire the rockets into the atmosphere. In a fairly short time, the algae will break down the carbon dioxide into oxygen and carbon.When the algae have done their work, the atmosphere will become cooler, but before man can set foot on Venus it will be necessary for the oxygen to produce rain. The surface of the planet will still be too hot for men to land on it but the rain will eventually fall and in a few years something like earth will be reproduced on Venus.On Venus there is a lot of__________.A. waterB. carbon dioxideC. carbon monoxideD. oxygen
Passage 2If the population of the earth goes on increasing at its present rate, there will eventually not be enough resources left to sustain life on the planet. By the middle of the 21st century, if present trends continue, we will have used up all the oil that drives our cars, for example. Even if scientists develop new ways of feeding the human race, the crowded conditions on earth will make it necessary for us to look for open space somewhere else. But none of the other planets in our solar system are capable of supporting life at present. One possible solution to the problem, however, has recently been suggested by an American scientist, Professor Carl Sagan.Sagan believes that before the earth's resources are completely exhausted it will be possible to change the atmosphere of Venus and so create a new world almost as large as earth itself. The difficulty is that Venus is much hotter than the earth and there is only a tiny amount of water there.Sagan proposes that algae organisms, which can live in extremely hot or cold atmospheres and at the same time produce oxygen, should be bred in conditions similar to those on Venus. As soon as this has been done, the algae will be placed in small rockets. Spaceships will then fly to Venus and fire the rockets into the atmosphere. In a fairly short time, the algae will break down the carbon dioxide into oxygen and carbon.When the algae have done their work, the atmosphere will become cooler, but before man can set foot on Venus it will be necessary for the oxygen to produce rain. The surface of the planet will still be too hot for men to land on it but the rain will eventually fall and in a few years something like earth will be reproduced on Venus. Man can eventually land on Venus only when__________.A. the algae have done their workB. the atmosphere becomes coolerC. there is oxygenD. it rains there
Passage 2If the population of the earth goes on increasing at its present rate, there will eventually not be enough resources left to sustain life on the planet. By the middle of the 21st century, if present trends continue, we will have used up all the oil that drives our cars, for example. Even if scientists develop new ways of feeding the human race, the crowded conditions on earth will make it necessary for us to look for open space somewhere else. But none of the other planets in our solar system are capable of supporting life at present. One possible solution to the problem, however, has recently been suggested by an American scientist, Professor Carl Sagan.Sagan believes that before the earth's resources are completely exhausted it will be possible to change the atmosphere of Venus and so create a new world almost as large as earth itself. The difficulty is that Venus is much hotter than the earth and there is only a tiny amount of water there.Sagan proposes that algae organisms, which can live in extremely hot or cold atmospheres and at the same time produce oxygen, should be bred in conditions similar to those on Venus. As soon as this has been done, the algae will be placed in small rockets. Spaceships will then fly to Venus and fire the rockets into the atmosphere. In a fairly short time, the algae will break down the carbon dioxide into oxygen and carbon.When the algae have done their work, the atmosphere will become cooler, but before man can set foot on Venus it will be necessary for the oxygen to produce rain. The surface of the planet will still be too hot for men to land on it but the rain will eventually fall and in a few years something like earth will be reproduced on Venus.CarlSagan believes that Venus might be colonized from earth because__________.A. it might be possible to change its atmosphereB. its atmosphere is the same as the earth'sC. there is a good supply of water on VenusD. the days on Venus are long enough
Passage 2If the population of the earth goes on increasing at its present rate, there will eventually not be enough resources left to sustain life on the planet. By the middle of the 21st century, if present trends continue, we will have used up all the oil that drives our cars, for example. Even if scientists develop new ways of feeding the human race, the crowded conditions on earth will make it necessary for us to look for open space somewhere else. But none of the other planets in our solar system are capable of supporting life at present. One possible solution to the problem, however, has recently been suggested by an American scientist, Professor Carl Sagan.Sagan believes that before the earth's resources are completely exhausted it will be possible to change the atmosphere of Venus and so create a new world almost as large as earth itself. The difficulty is that Venus is much hotter than the earth and there is only a tiny amount of water there.Sagan proposes that algae organisms, which can live in extremely hot or cold atmospheres and at the same time produce oxygen, should be bred in conditions similar to those on Venus. As soon as this has been done, the algae will be placed in small rockets. Spaceships will then fly to Venus and fire the rockets into the atmosphere. In a fairly short time, the algae will break down the carbon dioxide into oxygen and carbon.When the algae have done their work, the atmosphere will become cooler, but before man can set foot on Venus it will be necessary for the oxygen to produce rain. The surface of the planet will still be too hot for men to land on it but the rain will eventually fall and in a few years something like earth will be reproduced on Venus.In the long run, the most difficult problem caused by population growth on earth will probably be the lack of__________.查看材料A．foodB．oilC．spaceD．resources
Passage 2If the population of the earth goes on increasing at its present rate, there will eventually not be enough resources left to sustain life on the planet. By the middle of the 21st century, if present trends continue, we will have used up all the oil that drives our cars, for example. Even if scientists develop new ways of feeding the human race, the crowded conditions on earth will make it necessary for us to look for open space somewhere else. But none of the other planets in our solar system are capable of supporting life at present. One possible solution to the problem, however, has recently been suggested by an American scientist, Professor Carl Sagan.Sagan believes that before the earth's resources are completely exhausted it will be possible to change the atmosphere of Venus and so create a new world almost as large as earth itself. The difficulty is that Venus is much hotter than the earth and there is only a tiny amount of water there.Sagan proposes that algae organisms, which can live in extremely hot or cold atmospheres and at the same time produce oxygen, should be bred in conditions similar to those on Venus. As soon as this has been done, the algae will be placed in small rockets. Spaceships will then fly to Venus and fire the rockets into the atmosphere. In a fairly short time, the algae will break down the carbon dioxide into oxygen and carbon.When the algae have done their work, the atmosphere will become cooler, but before man can set foot on Venus it will be necessary for the oxygen to produce rain. The surface of the planet will still be too hot for men to land on it but the rain will eventually fall and in a few years something like earth will be reproduced on Venus.Algae are plants that can__________.查看材料A．live in very hot temperaturesB．live in very cold temperaturesC．manufacture oxygenD．all of the above
Passage 2If the population of the earth goes on increasing at its present rate, there will eventually not be enough resources left to sustain life on the planet. By the middle of the 21st century, if present trends continue, we will have used up all the oil that drives our cars, for example. Even if scientists develop new ways of feeding the human race, the crowded conditions on earth will make it necessary for us to look for open space somewhere else. But none of the other planets in our solar system are capable of supporting life at present. One possible solution to the problem, however, has recently been suggested by an American scientist, Professor Carl Sagan.Sagan believes that before the earth's resources are completely exhausted it will be possible to change the atmosphere of Venus and so create a new world almost as large as earth itself. The difficulty is that Venus is much hotter than the earth and there is only a tiny amount of water there.Sagan proposes that algae organisms, which can live in extremely hot or cold atmospheres and at the same time produce oxygen, should be bred in conditions similar to those on Venus. As soon as this has been done, the algae will be placed in small rockets. Spaceships will then fly to Venus and fire the rockets into the atmosphere. In a fairly short time, the algae will break down the carbon dioxide into oxygen and carbon.When the algae have done their work, the atmosphere will become cooler, but before man can set foot on Venus it will be necessary for the oxygen to produce rain. The surface of the planet will still be too hot for men to land on it but the rain will eventually fall and in a few years something like earth will be reproduced on Venus.CarlSagan believes that Venus might be colonized from earth because__________.查看材料A．it might be possible to change its atmosphereB．its atmosphere is the same as the earth'sC．there is a good supply of water on VenusD．the days on Venus are long enough
根据下列内容，回答196-200题。If the population of the earth goes on increasing at its present rate, there will eventually notbe enough resources left to sustain life on the planet. By the middle of the 21st century, if presenttrends continue, we will have used up all the oil that drives our cars, for example. Even if scien-tists develop new ways of feeding the human race, the crowded conditions on earth will make itnecessary for us to look for open space somewhere else. But none of the other planets in our solarsystem are capable of supporting life at present. One possible solution to the problem, however,has recently been suggested by an American scientist, Professor Carl Sagan.Sagan believes that before the earth's resources are completely exhausted it will be possible tochange the atmosphere of Venus and so create a new world almost as large as earth itself. The dif-ficulty is that Venus is much hotter than the earth and there is only a tiny amount of water there.Sagan proposes that algae organisms, which can live in extremely hot or cold atmospheres andat the same time produce oxygen, should be bred in conditions similar to those on Venus. As soonas this has been done, the algae will be placed in small rockets. Spaceships will then fly to Venusand fire the rockets into the atmosphere. In a fairly short time, the algae will break down the car-bon dioxide into oxygen and carbon.When the algae have done their work, the atmosphere will become cooler, but before mancan set foot on Venus it will be necessary for the oxygen to produce rain. The surface of the planetwill still be too hot for men to land on it but the rain will eventually fall and in a few years some-thing like earth will be reproduced on Venus.In the long run, the most difficult problem caused by population growth on earth willprobably be the lack of __________.A.foodB.oilC.spaceD.resources
If the population of the earth goes on increasing at its present rate, there will eventually not be enough resources left to sustain life on the planet.By the middle of the 21st century,if present trends continue, we will have used up all the oil that drives our cars,for example.Even if scientists develop new ways of feeding the human race,the crowded conditions on earth will make it necessary for lus to look for open space somewhere else. But none of the other planets in our solar system are capable of supporting life at present. One possible solution to the problem, however,has recently been suggested by American scientist, Professor Carl Sagan.Sagan believes that before the earth's resources are compleetely exhausted it will be possible to change the atmophere of Venus and so create a new world almost as large as earth itself. The difficult is that Venus is much hotter than the earth and there is only a tiny amount of water there.Sagan proposes that algae organisms that can live in extremely hot or cold atmospheres and at the same time produce oxygen,should be bred in condition similar to those on Venus.As soon as this has been done, the algae will be placed in small rockets. Spaceship will then fly to Venus and fire the rockets into the atmosphere .In a fairly short time, the alge will break down the carbon dioxide into oxygen and carbon.When the algae have done theri work, the atmosphere will become cooler,but befor man can set foot on Venus it will be neccessary for the oxygen to produce rain. The surface of the planet will still be too hot for man to land on it but the rain will eventually fall and in a few years something like earth will be reproduced on Venus.Inte long run, the most insoluble problem caused by population growth on earth will probably be the lack of ______.a.food b.oilc.spaced.resources
If the population of the earth goes on increasing at its present rate, there will eventually not be enough resources left to sustain life on the planet.By the middle of the 21st century,if present trends continue, we will have used up all the oil that drives our cars,for example.Even if scientists develop new ways of feeding the human race,the crowded conditions on earth will make it necessary for lus to look for open space somewhere else. But none of the other planets in our solar system are capable of supporting life at present. One possible solution to the problem, however,has recently been suggested by American scientist, Professor Carl Sagan.Sagan believes that before the earth's resources are compleetely exhausted it will be possible to change the atmophere of Venus and so create a new world almost as large as earth itself. The difficult is that Venus is much hotter than the earth and there is only a tiny amount of water there.Sagan proposes that algae organisms that can live in extremely hot or cold atmospheres and at the same time produce oxygen,should be bred in condition similar to those on Venus.As soon as this has been done, the algae will be placed in small rockets. Spaceship will then fly to Venus and fire the rockets into the atmosphere .In a fairly short time, the alge will break down the carbon dioxide into oxygen and carbon.When the algae have done theri work, the atmosphere will become cooler,but befor man can set foot on Venus it will be neccessary for the oxygen to produce rain. The surface of the planet will still be too hot for man to land on it but the rain will eventually fall and in a few years something like earth will be reproduced on Venus.Algae are plants that can____.a.live in very hot temperaturesb.live in very cold temperaturesc.manufacture oxygend.all of the above
If the population of the earth goes on increasing at its present rate, there will eventually not be enough resources left to sustain life on the planet.By the middle of the 21st century,if present trends continue, we will have used up all the oil that drives our cars,for example.Even if scientists develop new ways of feeding the human race,the crowded conditions on earth will make it necessary for lus to look for open space somewhere else. But none of the other planets in our solar system are capable of supporting life at present. One possible solution to the problem, however,has recently been suggested by American scientist, Professor Carl Sagan.Sagan believes that before the earth's resources are compleetely exhausted it will be possible to change the atmophere of Venus and so create a new world almost as large as earth itself. The difficult is that Venus is much hotter than the earth and there is only a tiny amount of water there.Sagan proposes that algae organisms that can live in extremely hot or cold atmospheres and at the same time produce oxygen,should be bred in condition similar to those on Venus.As soon as this has been done, the algae will be placed in small rockets. Spaceship will then fly to Venus and fire the rockets into the atmosphere .In a fairly short time, the alge will break down the carbon dioxide into oxygen and carbon.When the algae have done theri work, the atmosphere will become cooler,but befor man can set foot on Venus it will be neccessary for the oxygen to produce rain. The surface of the planet will still be too hot for man to land on it but the rain will eventually fall and in a few years something like earth will be reproduced on Venus.Carl Sagan believes that Venus might be colonized from earth because _____a.it might be possible to change its atmosphereb.its atmosphere is the same as the earth'sc.there is a good supply of water on Venusd.the days on Venus are long enough
The population of the earth（）increasing fast. One third of the population here（）workers.Ais;areBis;hasbeenCare;isDis;was
The population of the earth（）increasing fast. One third of the population here（）workers.A、is;areB、is;hasbeenC、are;isD、is;was
Which two statements are true about bandwidth guarantee？（）A、When congestion is present，the priority command doesn’t allow exceeding the allocated rateB、When congestion isn’t present，the priority command doesn’t allow exceeding the allocated rateC、When congestion is present，the priority command allows exceeding the allocated rateD、When congestion isn’t present，the priority command allows exceeding the allocated rate
单选题Since 1960, the fast-growing town of Hotstone, Arizona, has drawn water from the Gray River, which feeds Lake Mudfish. If the town’s water use continues to grow at its present rate, in about 20 years the water level of Lake Mudfish will inevitably decrease to the point that it can no longer support its biologically fragile population of fish. The prediction above is based on which of the following assumptions?AAs the town’s water requirements grow, it will not be able to meet those requirements by drawing on water sources other than the Gray River.BSince 1960, the lake’s population of fish has become more biologically fragile.CThe amount of water that the lake loses to evaporation each year will increase over the next two decades.DThere are multiple sources of water besides the Gray River that feed into Lake Mudfish.EThe town of Hotstone will be able to reverse its trend of increasing water use if it implements an aggressive water conservation program.
问答题Practice 1 Biological diversity, or biodiversity, means the variety of life on earth and includes the entire web of living organisms ranging from soil microbes, frogs, and trees to bears and blue whales. From the perspective of sustainable use, wildlife is a renewable resource that provides many benefits and socioeconomic advantages. Sustainable use is defined as “the use of components of biodiversity in a way and at a rate that does not lead to long term decline” but maintains the “potential to meet the needs and aspirations of present and future generations.”
单选题The population of the earth（）increasing fast. One third of the population here（）workers.Ais;areBis;hasbeenCare;isDis;was
问答题Practice 10 What we today call American folk art was, art of, by, and for ordinary, everyday I “folks” who, with increasing prosperity and leisure, created a market for art of all kinds, and especially for portraits. Citizens of prosperous, essentially middle-class republics—whether ancient Romans，seventeenth-century Dutch burghers, or nineteenth-century Americans—have always shown a marked taste for portraiture. Starting in the late eighteenth century, the United States contained an increasing number of such people, and of the artists who could meet their demands. The earliest American folk art portraits come, not surprisingly, from New England—especially Connecticut and Massachusetts—for this was a wealthy and populous region and the center of a strong craft tradition. Within a few decades after the signing of the Declaration of Independence in 1776, the population was pushing westward, and the portrait painters could be found at work in western New York, Ohio, Kentucky, Illinois, and Missouri. Midway through its first century as a nation, the United States' population had increased roughly five times, and eleven new states had been added to original thirteen. During these years, the demand for portraits grew and grew, eventually to be satisfied by camera.
问答题练习16 (1) Actually, the world’s birth rate is falling. But so is death rate, as medical advances have made it possible for man to live longer than before. Such advances have also reduced baby death rate. (2) Unless population growth is reduced, the world population may reach 12 billion in a century. Is the earth capable of providing a good life for so large a population?
单选题One reason for quick population increase in underdeveloped countries is that ______.Athose countries encourage people to have large familiesBpeople can get government support if they have more kidsCimproved public health standards have reduced death rate greatlyDthose countries have enough resources to support a large population