问答题Scientists have long assumed that most of the ice that melted was in the Northern hemisphere（半球） during the 30,000-year long ice age.
问答题
Scientists have long assumed that most of the ice that melted was in the Northern hemisphere（半球） during the 30,000-year long ice age.
参考解析
解析：
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共用题干1. Icebergs are among nature's most spectacular（壮观的）creations , and yet most people have never seen one.A vague air of mystery envelops them.They come into being somewhere in faraway, frigid waters,amid thunderous noise and splashing turbulence,which in most case no one hears or sees. They exist only a short time and then slowly waste away（消融）just as unnoticed.2. Objects of sheerest（最纯粹的）beauty they have been called. Appearing in an endless vaniety of shapes,they may be dazzlingly white,or they may be glassy blue,green or purple,tinted faintly on in darker hues.They are graceful, stately,inspiring in calm,sunlight seas.3.But they are also called frightening and dangerous,and that they are一in the night,in the fog,and in storms.Even in clear weather one is wise to stay a safe distance away from them.Most of their bulk is hidden below the water,so their underwater parts may extend out far beyond the visible top.Also,they may roll over unexpectedly,churning the waters around them.4.Icebergs are parts of glaciers that break off,drift into the water,float about awhile,and finally melt.Icebergs afloat today are made of snowflakes that have fallen over long ages of time.They embody snows that drifted down hundreds,or many thousands,or in some cases maybe a million years ago.The snows fell in polar region and on cold mountains,where they melted only a little or not at all,and so collected to great depths over the years and centuries.As each year's snow accumulation lay on the surface,evaporation and melting caused the snowflakes slowly to lose their feathery points and become tiny grains of ice.When new snow fell on top of the old,it too turned to icy grains.So blankets of snow and ice grains mounted layer upon layer and were of such great thickness that the weight of the upper layers compressed the lower ones.With time and pressure from above, the many small ice grains joined and changed to larger crystals,and eventually the deeper crystals merged into a solid mass of ice.With time and pressure from above,the many small ice grains joined and changed to__________, and eventually the deeper crystals merged into a solid mass of ice.A:larger than the part above the waterB:stay near the icebergC:melt away just as unnoticedD:larger crystalsE:stay away from icebergF:above the water
共用题干U. S. Scientists Confirm Water on MarsNASA scientists said that Mars was covered once by vast lakes,flowing rivers and a Va-riety of other wet environments that had the potential to support life.Laboratory tests aboard NASA's Phoenix Mars Lander have identified water in a soil sample;the lander's robotic arm delivered the sample Wednesday to an instrument that iden-tifies vapors produced by the heating of samples.“We have water,”said William Boynton of the University of Arizona,lead scientist for ,the Thermal and Evolved-Gas Analyzer,or TEGA.“This is the first time Martian water has been touched and tasted.”The robotic arm is a critical part of the Phoenix Mars mission. It is needed to trench into the icy layers of northern polar Mars and deliver samples to instruments that will analyze what Mars is made of,what its water is like,and whether it is or has ever been a possible habitat for life.The soil sample came from a trench approximately 2 inches deep.When the robotic arm first reached that depth,it hit a hard layer of frozen soil.Two attempts to deliver samples of icy soil on days when fresh material was exposed were foiled when the samples became stuck inside the scoop.Most of the material in Wednesday's sample had been exposed to the air for two days,letting some of the water in the sample vaporize away and making the soil easier to handle.“Mars is giving us some surprises,”said Phoenix principal investigator Peter Smith of the University of Arizona.“We're excited because surprises are where discoveries come from. One surprise is how the soil is behaving. The ice-rich layers stick to the scoop when poised in the sun above the deck,different from what we expected,from all the Mars simulation tes-ting we've done so far.”Since landing on May 25,Phoenix has been studying soil with a chemistry lab,TEGA, a microscope,a conductivity probe and cameras.The science team is trying to determine whether the water ice ever thaws enough to be available for biology and if carbon-containing chemicals and other raw materials for life are present.The mission is examining the sky as well as the ground. A Canadian instrument is using a laser beam to study dust and clouds overhead.“It's a 30-watt light bulb giving us a laser show on Mars,”said Victoria Hipkin of the Canadian Space Agency.A full-circle,color panorama of Phoenix's surroundings also has been completed by the spacecraft.“The details and patterns we see in the ground show an ice-dominated terrain as far as the eye can see,”said Mark Lemmon of Texas A & M University,lead scientist forPhoenix's Surface Stereo Imager camera.“They help us plan measurements we're making within reach of the robotic arm and interpret those measurements on a wider scale.”Which one of the following statements is NOT meant by the writer?A: Scientists have been trying to break the ice-rich layers of soil on Mars.B: Scientists have been surprised by how the soil on Mars behaves.C: Scientists have been trying to find out if there is life supporting material on Mars.D: Scientists have been trying to know if water ice will melt.
Friends might not be always trust-worthy, but dogs are; they have long been regarded as the most( )company of human beings.A.reliableB.regularC.reluctantD.religious
共用题干Europa's Watery UnderworldEuropa,one of Jupiter's 63 known moons,looks bright and icy on the surface.But appearances can be deceiving:Miles within its cracked,frigid shell,Europa probably hides giant pools of liquid water. Where scientists find liquid water,they hope to find life as well.Since we can't go diving into Europa's depths just yet,scientists instead have to investigate the moon's surface for clues to what lies beneath.In a new study,scientists investigated one group of strange ice patterns on Europa and concluded that the formations mark the top of an underground pool that holds as much water as the U.S.Great Lakes.Pictures of Europa,which is slightly smaller than Earth's moon,clearly show a tangled,icy mishmash of lines and cracks known as"chaos terrains".These chaotic places cover more than half of Europa. For more than 10 years,scientists have wondered what causes the formations.The new study suggests that they arise from the mixing of vast underground stores of liquid water with icy material near the surface.For scientists who suspect that Europa also may be hiding life beneath its icy surface,the news about the new lake is exciting."It would be great if these lakes harbored life,"Britney Schmidt,a planetary scientist who worked onthe study,told Science News."But even if they didn't,they say that Europa is doing something interesting and active right now."Schmidt,a scientist at the University of Texas at Austin,and her colleagues wanted to know how chaos terrains form.Since they couldn't rocket to Europa to see for themselves,they searched for similar forma- tions here on Earth.They studied collapsed ice shelves in Antarctica and icy caps on volcanoes in Iceland. Those features on Earth formed when liquid water mixed with ice.The scientists now suspect something similar might be happening on Europa:that as water and ice of different temperatures mingle and shift,the surface fractures.This would explain the jumbled ice sculptures."Fracturing catastrophically disrupts the ice in the same way that it causes ice shelves to collapse on Earth,"Schmidt told Science News.She and her team found that the process could be causing chaos terrains to form quickly on Europa.The new study suggests that on this moon,elements such as oxygen from the surface blend with the deep bodies of water. That mixture may create an environment that supports life.Schmidt and her colleagues are the first group of scientists reaching Europa.A:RightB:WrongC:Not mentioned
共用题干Europa's Watery UnderworldEuropa,one of Jupiter's 63 known moons,looks bright and icy on the surface.But appearances can be deceiving:Miles within its cracked,frigid shell,Europa probably hides giant pools of liquid water. Where scientists find liquid water,they hope to find life as well.Since we can't go diving into Europa's depths just yet,scientists instead have to investigate the moon's surface for clues to what lies beneath.In a new study,scientists investigated one group of strange ice patterns on Europa and concluded that the formations mark the top of an underground pool that holds as much water as the U.S.Great Lakes.Pictures of Europa,which is slightly smaller than Earth's moon,clearly show a tangled,icy mishmash of lines and cracks known as"chaos terrains".These chaotic places cover more than half of Europa. For more than 10 years,scientists have wondered what causes the formations.The new study suggests that they arise from the mixing of vast underground stores of liquid water with icy material near the surface.For scientists who suspect that Europa also may be hiding life beneath its icy surface,the news about the new lake is exciting."It would be great if these lakes harbored life,"Britney Schmidt,a planetary scientist who worked onthe study,told Science News."But even if they didn't,they say that Europa is doing something interesting and active right now."Schmidt,a scientist at the University of Texas at Austin,and her colleagues wanted to know how chaos terrains form.Since they couldn't rocket to Europa to see for themselves,they searched for similar forma- tions here on Earth.They studied collapsed ice shelves in Antarctica and icy caps on volcanoes in Iceland. Those features on Earth formed when liquid water mixed with ice.The scientists now suspect something similar might be happening on Europa:that as water and ice of different temperatures mingle and shift,the surface fractures.This would explain the jumbled ice sculptures."Fracturing catastrophically disrupts the ice in the same way that it causes ice shelves to collapse on Earth,"Schmidt told Science News.She and her team found that the process could be causing chaos terrains to form quickly on Europa.The new study suggests that on this moon,elements such as oxygen from the surface blend with the deep bodies of water. That mixture may create an environment that supports life.The liquid water of an underground pool of Europa is estimated as much as the volume of the U.S.Great Lakes.A:RightB:WrongC:Not mentioned
共用题干Europa's Watery UnderworldEuropa,one of Jupiter's 63 known moons,looks bright and icy on the surface.But appearances can be deceiving:Miles within its cracked,frigid shell,Europa probably hides giant pools of liquid water. Where scientists find liquid water,they hope to find life as well.Since we can't go diving into Europa's depths just yet,scientists instead have to investigate the moon's surface for clues to what lies beneath.In a new study,scientists investigated one group of strange ice patterns on Europa and concluded that the formations mark the top of an underground pool that holds as much water as the U.S.Great Lakes.Pictures of Europa,which is slightly smaller than Earth's moon,clearly show a tangled,icy mishmash of lines and cracks known as"chaos terrains".These chaotic places cover more than half of Europa. For more than 10 years,scientists have wondered what causes the formations.The new study suggests that they arise from the mixing of vast underground stores of liquid water with icy material near the surface.For scientists who suspect that Europa also may be hiding life beneath its icy surface,the news about the new lake is exciting."It would be great if these lakes harbored life,"Britney Schmidt,a planetary scientist who worked onthe study,told Science News."But even if they didn't,they say that Europa is doing something interesting and active right now."Schmidt,a scientist at the University of Texas at Austin,and her colleagues wanted to know how chaos terrains form.Since they couldn't rocket to Europa to see for themselves,they searched for similar forma- tions here on Earth.They studied collapsed ice shelves in Antarctica and icy caps on volcanoes in Iceland. Those features on Earth formed when liquid water mixed with ice.The scientists now suspect something similar might be happening on Europa:that as water and ice of different temperatures mingle and shift,the surface fractures.This would explain the jumbled ice sculptures."Fracturing catastrophically disrupts the ice in the same way that it causes ice shelves to collapse on Earth,"Schmidt told Science News.She and her team found that the process could be causing chaos terrains to form quickly on Europa.The new study suggests that on this moon,elements such as oxygen from the surface blend with the deep bodies of water. That mixture may create an environment that supports life.Europa is the most recently discovered one among Jupiter's moons.A:RightB:WrongC:Not mentioned
共用题干Europa's Watery UnderworldEuropa,one of Jupiter's 63 known moons,looks bright and icy on the surface.But appearances can be deceiving:Miles within its cracked,frigid shell,Europa probably hides giant pools of liquid water. Where scientists find liquid water,they hope to find life as well.Since we can't go diving into Europa's depths just yet,scientists instead have to investigate the moon's surface for clues to what lies beneath.In a new study,scientists investigated one group of strange ice patterns on Europa and concluded that the formations mark the top of an underground pool that holds as much water as the U.S.Great Lakes.Pictures of Europa,which is slightly smaller than Earth's moon,clearly show a tangled,icy mishmash of lines and cracks known as"chaos terrains".These chaotic places cover more than half of Europa. For more than 10 years,scientists have wondered what causes the formations.The new study suggests that they arise from the mixing of vast underground stores of liquid water with icy material near the surface.For scientists who suspect that Europa also may be hiding life beneath its icy surface,the news about the new lake is exciting."It would be great if these lakes harbored life,"Britney Schmidt,a planetary scientist who worked onthe study,told Science News."But even if they didn't,they say that Europa is doing something interesting and active right now."Schmidt,a scientist at the University of Texas at Austin,and her colleagues wanted to know how chaos terrains form.Since they couldn't rocket to Europa to see for themselves,they searched for similar forma- tions here on Earth.They studied collapsed ice shelves in Antarctica and icy caps on volcanoes in Iceland. Those features on Earth formed when liquid water mixed with ice.The scientists now suspect something similar might be happening on Europa:that as water and ice of different temperatures mingle and shift,the surface fractures.This would explain the jumbled ice sculptures."Fracturing catastrophically disrupts the ice in the same way that it causes ice shelves to collapse on Earth,"Schmidt told Science News.She and her team found that the process could be causing chaos terrains to form quickly on Europa.The new study suggests that on this moon,elements such as oxygen from the surface blend with the deep bodies of water. That mixture may create an environment that supports life.The strange ice patterns on Europa are formed as a result of a mixture of liquid water and solid material underground water pool.A:RightB:WrongC:Not mentioned
资料：A high-precision NASA radar instrument left a NASA airport in Southern California for Iceland on January 28 to create detailed maps of how glaciers move in the dead of winter. This will help scientists around the world better understand some of the most basic processes involved in melting glaciers, which are major contributors to rising sea levels.NASA used the same airborne instrument in June 2012 to map the summer flows of two Icelandic ice caps. The ice caps — large areas of permanent snow and ice cover — encompass multiple glaciers flowing in different directions and at different speeds. By mapping the same ice caps now, in winter, when the surface remains frozen all day, and then comparing the winter and summer velocities, the researchers will be able to isolate the effects of melt water.Above is a view of a small part of the Hofsjkull ice cap, which encompasses several glaciers. The fan at upper left is part of a glacier called Mlaj?kull.For more on the research, see this NASA press release.What does the underlined word permanent （paragragh 2） mean?A.Freeze easily.B.Move quickly.C.Long-lasting.D.Extremely cold.
资料：A high-precision NASA radar instrument left a NASA airport in Southern California for Iceland on January 28 to create detailed maps of how glaciers move in the dead of winter. This will help scientists around the world better understand some of the most basic processes involved in melting glaciers, which are major contributors to rising sea levels.NASA used the same airborne instrument in June 2012 to map the summer flows of two Icelandic ice caps. The ice caps — large areas of permanent snow and ice cover — encompass multiple glaciers flowing in different directions and at different speeds. By mapping the same ice caps now, in winter, when the surface remains frozen all day, and then comparing the winter and summer velocities, the researchers will be able to isolate the effects of melt water.Above is a view of a small part of the Hofsjkull ice cap, which encompasses several glaciers. The fan at upper left is part of a glacier called Mlaj?kull.For more on the research, see this NASA press release.How can the scientists figure out the effects of melting water?A.By melting the frozen iceberg in winter.B.By observing the snow's moving directions.C.By isolating ice from water in sunlines.D.By comparing the glaciers moving speeds.
Scientists say climate change and human activity have increasingly led to the melting of ______ pieces of Antarctic ice.A.massiveB.quantitativeC.surplusD.formidable
共用题干Natural MedicinesSince earliest days,humans have used some kinds of medicines.We know this because humans have survived.Ancient treatments for injury and disease were successful enough to keep humans from dying out completely.They were successful long before the time of modern medicine. Before the time of doctors with white coats and shiny（发亮的）instruments. Before the time of big hospitals with strange and wonderful equipment.Many parts of the world still do not have university-educated doctors. Nor do they have expensive hospitals.Yet injuries are treated.And diseases are often cured.How?By ancient methods. By medicines that might seem mysterious , even magical（有魔力的）.Traditional medicines are neither mysterious nor magical,however.Through the centuries , tribal（部落的）medicine men experimented with plants. They found many useful chemicals in the plants.And scientists believe many of these traditional medicines may provide the cure for some of today's most serious diseases.Experts say almost 80% of the people in the world use plants for health care.These natural medicines are used not just because people have no other form of treatment. They are used because people trust them. In developed areas,few people think about the source of the medicines they buy in a store .Yet many widely-used medicines are from ancient sources,especially plants.Some experts say more than 25%of modem medicines come,in one way or another,from nature.Scientists have long known that nature is really a chemical factory. All living things contain chemicals that help them survive .So scientists' interest in traditional medicine is not new.But it has become an urgent concern.This is because the earth's supply of natural medicines may be dropping rapidly. It is believed by scientists that traditional medicines______.A: can cure all kinds of diseasesB: may cure some of today's most serious diseasesC: are no longer useful for modern menD: are too cheap to be useful
共用题干第一篇Arctic MeltEarth’s North and South Poles are famous for being cold and icy.Last year,however,the amnount of ice in the Arctic Ocean（北冰洋）fell to a record low.Normally,ice builds in Arctic waters around the North Pole each winter and shrinks（缩小）during the summer. But for many years,the amount of ice left by the end of summer has been declining.Since 1979,each decade has seen an 11.4 percent drop in end?of-summer ice cover. Between 1981 and 2000,ice in the Arctic lost 22 percent of its thickness,becoming I.13 meters thinner.Last summer,Arctic sea ice reached its thinnest levels yet.By the end of summer 2007,the ice had shrunk to cover just 4.2 million square kilometers.That's 38 percent less area than the average cover at that time of year. And it's a very large 23 percent below the previous record low,which was set just 2 years ago. This continuing trend has made scientists concerned.There may be several reasons for the ice melt, says Jinlun Zhang, an oceanographer（海洋学家）at the University of Washington at Seattle.Unusually strong winds blew through the Arctic last summer. The winds pushed much of the ice out of the central Arctic,leaving a large area of thin ice and open water.Scientists also suspect that fewer clouds cover the Arctic now than in the past.Clearer skies allow more sunlight to reach the ocean.The extra heat warms both the water and the atmosphere.In parts of the Arctic Ocean last year,surface temperatures were 3.5℃warmer than average and 1.5℃warmer than the previous record high.With both air and water getting warmer,the ice is melting from both above and below. In some parts of the Beaufort Sea,north of Alaska and western Canada,ice that measured 3.3 meters thick at the beginning of the summer measured just 50 centimeters by season's end.The new measurements suggest that melting is far more severe than scientists have seen by just looking at ice covcrfrom above,says Donald K. Perovich,a geophysicist at the U.S.Army Cold Regions Researchand Engineering Laboratory in Hanover,N.H.Some scientists fear that the Arctic is stuck in a warming trend from which it may never recover.By the end of summer 2007 the ice cover in the Arctic was ________.A:4.2 million square kilometersB:11.4 million square kilometersC:1.13 million square kilometers D:38 million square kilometers
共用题干第一篇Arctic MeltEarth’s North and South Poles are famous for being cold and icy.Last year,however,the amnount of ice in the Arctic Ocean（北冰洋）fell to a record low.Normally,ice builds in Arctic waters around the North Pole each winter and shrinks（缩小）during the summer. But for many years,the amount of ice left by the end of summer has been declining.Since 1979,each decade has seen an 11.4 percent drop in end?of-summer ice cover. Between 1981 and 2000,ice in the Arctic lost 22 percent of its thickness,becoming I.13 meters thinner.Last summer,Arctic sea ice reached its thinnest levels yet.By the end of summer 2007,the ice had shrunk to cover just 4.2 million square kilometers.That's 38 percent less area than the average cover at that time of year. And it's a very large 23 percent below the previous record low,which was set just 2 years ago. This continuing trend has made scientists concerned.There may be several reasons for the ice melt, says Jinlun Zhang, an oceanographer（海洋学家）at the University of Washington at Seattle.Unusually strong winds blew through the Arctic last summer. The winds pushed much of the ice out of the central Arctic,leaving a large area of thin ice and open water.Scientists also suspect that fewer clouds cover the Arctic now than in the past.Clearer skies allow more sunlight to reach the ocean.The extra heat warms both the water and the atmosphere.In parts of the Arctic Ocean last year,surface temperatures were 3.5℃warmer than average and 1.5℃warmer than the previous record high.With both air and water getting warmer,the ice is melting from both above and below. In some parts of the Beaufort Sea,north of Alaska and western Canada,ice that measured 3.3 meters thick at the beginning of the summer measured just 50 centimeters by season's end.The new measurements suggest that melting is far more severe than scientists have seen by just looking at ice covcrfrom above,says Donald K. Perovich,a geophysicist at the U.S.Army Cold Regions Researchand Engineering Laboratory in Hanover,N.H.Some scientists fear that the Arctic is stuck in a warming trend from which it may never recover.It can be learned from the last sentence that _________.A:the ice melt in the Arctic may never stopB:scientists are trying hard to stop the ice melt in the ArcticC:scientists are delighted to find out what is going on in the ArcticD:the warming trend in the Arctic can be reversed in the near future
共用题干第一篇Arctic MeltEarth’s North and South Poles are famous for being cold and icy.Last year,however,the amnount of ice in the Arctic Ocean（北冰洋）fell to a record low.Normally,ice builds in Arctic waters around the North Pole each winter and shrinks（缩小）during the summer. But for many years,the amount of ice left by the end of summer has been declining.Since 1979,each decade has seen an 11.4 percent drop in end?of-summer ice cover. Between 1981 and 2000,ice in the Arctic lost 22 percent of its thickness,becoming I.13 meters thinner.Last summer,Arctic sea ice reached its thinnest levels yet.By the end of summer 2007,the ice had shrunk to cover just 4.2 million square kilometers.That's 38 percent less area than the average cover at that time of year. And it's a very large 23 percent below the previous record low,which was set just 2 years ago. This continuing trend has made scientists concerned.There may be several reasons for the ice melt, says Jinlun Zhang, an oceanographer（海洋学家）at the University of Washington at Seattle.Unusually strong winds blew through the Arctic last summer. The winds pushed much of the ice out of the central Arctic,leaving a large area of thin ice and open water.Scientists also suspect that fewer clouds cover the Arctic now than in the past.Clearer skies allow more sunlight to reach the ocean.The extra heat warms both the water and the atmosphere.In parts of the Arctic Ocean last year,surface temperatures were 3.5℃warmer than average and 1.5℃warmer than the previous record high.With both air and water getting warmer,the ice is melting from both above and below. In some parts of the Beaufort Sea,north of Alaska and western Canada,ice that measured 3.3 meters thick at the beginning of the summer measured just 50 centimeters by season's end.The new measurements suggest that melting is far more severe than scientists have seen by just looking at ice covcrfrom above,says Donald K. Perovich,a geophysicist at the U.S.Army Cold Regions Researchand Engineering Laboratory in Hanover,N.H.Some scientists fear that the Arctic is stuck in a warming trend from which it may never recover.The Beaufort Sea mentioned in Paragraph 7 is an example to show_________. A:how acetirate the new measurements areB:how thick the ice is in itC:how serious the problem of the ice melt in the Arctic isD:how dangerous it is to travel to it
共用题干第一篇Arctic MeltEarth’s North and South Poles are famous for being cold and icy.Last year,however,the amnount of ice in the Arctic Ocean（北冰洋）fell to a record low.Normally,ice builds in Arctic waters around the North Pole each winter and shrinks（缩小）during the summer. But for many years,the amount of ice left by the end of summer has been declining.Since 1979,each decade has seen an 11.4 percent drop in end?of-summer ice cover. Between 1981 and 2000,ice in the Arctic lost 22 percent of its thickness,becoming I.13 meters thinner.Last summer,Arctic sea ice reached its thinnest levels yet.By the end of summer 2007,the ice had shrunk to cover just 4.2 million square kilometers.That's 38 percent less area than the average cover at that time of year. And it's a very large 23 percent below the previous record low,which was set just 2 years ago. This continuing trend has made scientists concerned.There may be several reasons for the ice melt, says Jinlun Zhang, an oceanographer（海洋学家）at the University of Washington at Seattle.Unusually strong winds blew through the Arctic last summer. The winds pushed much of the ice out of the central Arctic,leaving a large area of thin ice and open water.Scientists also suspect that fewer clouds cover the Arctic now than in the past.Clearer skies allow more sunlight to reach the ocean.The extra heat warms both the water and the atmosphere.In parts of the Arctic Ocean last year,surface temperatures were 3.5℃warmer than average and 1.5℃warmer than the previous record high.With both air and water getting warmer,the ice is melting from both above and below. In some parts of the Beaufort Sea,north of Alaska and western Canada,ice that measured 3.3 meters thick at the beginning of the summer measured just 50 centimeters by season's end.The new measurements suggest that melting is far more severe than scientists have seen by just looking at ice covcrfrom above,says Donald K. Perovich,a geophysicist at the U.S.Army Cold Regions Researchand Engineering Laboratory in Hanover,N.H.Some scientists fear that the Arctic is stuck in a warming trend from which it may never recover.What are the reasons for the ice melting according to the scientists?A:Strong winds and clear skits.B:Longer summers and shorter winters.C:Open water and thin ice.D:Heavy clouds and light winds.
共用题干第一篇Arctic MeltEarth’s North and South Poles are famous for being cold and icy.Last year,however,the amnount of ice in the Arctic Ocean（北冰洋）fell to a record low.Normally,ice builds in Arctic waters around the North Pole each winter and shrinks（缩小）during the summer. But for many years,the amount of ice left by the end of summer has been declining.Since 1979,each decade has seen an 11.4 percent drop in end?of-summer ice cover. Between 1981 and 2000,ice in the Arctic lost 22 percent of its thickness,becoming I.13 meters thinner.Last summer,Arctic sea ice reached its thinnest levels yet.By the end of summer 2007,the ice had shrunk to cover just 4.2 million square kilometers.That's 38 percent less area than the average cover at that time of year. And it's a very large 23 percent below the previous record low,which was set just 2 years ago. This continuing trend has made scientists concerned.There may be several reasons for the ice melt, says Jinlun Zhang, an oceanographer（海洋学家）at the University of Washington at Seattle.Unusually strong winds blew through the Arctic last summer. The winds pushed much of the ice out of the central Arctic,leaving a large area of thin ice and open water.Scientists also suspect that fewer clouds cover the Arctic now than in the past.Clearer skies allow more sunlight to reach the ocean.The extra heat warms both the water and the atmosphere.In parts of the Arctic Ocean last year,surface temperatures were 3.5℃warmer than average and 1.5℃warmer than the previous record high.With both air and water getting warmer,the ice is melting from both above and below. In some parts of the Beaufort Sea,north of Alaska and western Canada,ice that measured 3.3 meters thick at the beginning of the summer measured just 50 centimeters by season's end.The new measurements suggest that melting is far more severe than scientists have seen by just looking at ice covcrfrom above,says Donald K. Perovich,a geophysicist at the U.S.Army Cold Regions Researchand Engineering Laboratory in Hanover,N.H.Some scientists fear that the Arctic is stuck in a warming trend from which it may never recover.Which of the following is closest in meaning to the word"build"in the first sentence of thesecond paragraph?A:Construct.B:Establish.C:Create.D:Expand.
单选题_____ the calculation is right, scientists can never be sure that they have included all variables and modeled them accurately.AEven ifBAs far asCIf onlyDSo long as
问答题The approximately 65,000 images the Surveyor orbiter has beamed home in the nearly three years it has been circling Mars are full of this kind of expected hydro-scarring. But some of the pictures took scientists by surprise. The older a formation is, the more likely it is to have been distorted over the eons--smoothed by periodic windstorms or gouged by the occasional incoming meteor. However, a few of the newly discovered water channels look flesh. That discovery has lead astonished researchers to conclude that these channels may have been recently formed. Paleontologists have long assumed that if underground water was going to bubble up on Mars, it would have to be somewhere in the balmy equatorial zones, where temperatures at noon in midsummer may reach 68 degrees Fahrenheit (20 degrees Centigrade). Almost all the new channels, however, were discovered at the planet’s relative extremes--north of 30 degrees north latitude and south of 30 degrees south latitude--and all were carved on the cold, shaded sides of slopes.
单选题The scientists are not sure_______.Ahow long the ice age lastedBwhere ice sheets melted during the ice ageCwhat caused the temperature changesDwhat the earth is made up of
单选题It is assumed that students at an intermediate level will have a good（）of the basic structures and vocabulary of English.AcommandBcommandingCto commandDcommanded
问答题Scientists hope that a remote lake on a dormant Chilean volcano can provide clues to what life may have been like in a far more distant place—the planet Mars.A 10-member team placed special plates in the lake on Licancabur volcano, at an altitude of 20,000 feet，on Sunday to measure the effects of ultraviolet light on organisms living there.The scientists, mostly from the United States, think learning how Licancabur organisms protect themselves may help researchers understand how life survived on early Earth and perhaps on early Mars as well.The damaging effects of UV radiation intensify at altitude and the air is very thin. And the lake is covered with ice most of the year, as would have been bodies of water on Mars.“If there was life on Mars 3.5 billion years ago, it could have used defense mechanisms similar to those used by the organisms at Licancabur volcano to survive,” said team leader Nathalie Cabrol.
单选题Which of the following is the best title for the passage ?AA computer modelBStudies show ice melted equally in the North and the South during the ice ageCMost of the ice melted in the Northern hemisphere during the 30,000-year long ice ageDA survey result