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英语首字母填空练习题及答案

Everything on the earth _____ all the time.

A. is changing

B. is changed

C. has changed

D. has been changed


参考答案： A

It has been proven that on the Earth, the closer one stays to the Earth, the more slowly time would seem to go.()

此题为判断题(对，错)。


正确答案：正确

Our teacher told us that the earth__________ (be) round．


正确答案：
41.is

Passage 2
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 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. water
B. carbon dioxide
C. carbon monoxide
D. oxygen

答案：B
解析：
由第--f&的最后一句话中的“there is only a tiny amount ofwater there(Venus)”得知，A选项错误。第三段结尾说明，藻类通过火箭运往金星，然后“In a fairly short time，the algae will break down the carbon dioxide into oxygen and carbon”.说明金星上有大量的二氧化碳。C和D选项错误。故选B。

Passage 2
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 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 work
B. the atmosphere becomes cooler
C. there is oxygen
D. it rains there

答案：D
解析：
由最后一段中“before man can set foot on Venus it will be necessary for the oxygen to produce rain”可知，只有金星上有降雨，人类才最终有可能在上面着陆。所以正确答案为D。

英语首字母填空练习题及答案The u means the earth , the sun , the moon and the stars and the space b them . Many of the stars are so f away that we can not see them The moon , our satellite ,travels a the earth . It has already been visited b man from the earth . Man-made satellites have been sent up i space by many countries . They go round the earth . They areused for helping us to learn more a the earth , the weather and other things . They are also used for sending and r messages . It makes people f different countriesunderstand each other much better . So people say the world itself is becoming a much s place. People call the small place the global village1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 答案：1. universe 2. between 3. far 4. around 5. by ,6. into 7. about 8.receiving 9. from 10. smaller .A： G lafternoon. What can I do for you ?B: Yes, please. Id like 想要 to see a T- shirt.A： What c 2 do you like?B: I like pink very m 3.A: S 4, we dont have any pink T-shirts. B 5 we have some brown o 6.B: Let me see.A: OK, h 7 ere you are.B: Oh, the color is very nice. Can I try 试穿 i 8?A: Sure. You，re c 9_ool.B: T 10 you.答案：1. Good2. color3. much4. Sorry5. But6. ones7. here8. it9. cool10. Thank.Henry was worried. This was his first time to go traveling by air. He did not know h to find his seat, so he went to the air hostess and asked, “Could you help me? I cant find my seat.”The air hostess s him the seat and told him to sit d and fasten the seat belt. She told Henry not to m about when the plane was going up. And she also said that Henrys earsmight feel a little s, but he didnt need to worry about it b many people felt like that. When the plane was f very high, Henry could stand up and walk round. He coulde read books, newspapers or see films. The air hostess would b food and drinks. Henry could e the flight and arrived home soon.1. 2. 3. 4. 5. 6.7.8.9.10.答案:1. how 2. showed 3. down 4. move 5. strange ,6. because 7. flying 8. either 9. bringlO. enjoy感谢您的阅读，祝您生活愉快。

Passage 2
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 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 atmosphere
B. its atmosphere is the same as the earth's
C. there is a good supply of water on Venus
D. the days on Venus are long enough

答案：A
解析：
由第二段第一句中的“itwill be possible to change the atmosphere ofVenus and so create a new worl d”可知.so是表示因果的连接词，前因后果，所以正确答案A。

Passage 2
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 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．food
B．oil
C．space
D．resources

答案：C
解析：
由第一段可知，如果人口按照目前速度持续膨胀的话，地球上最终会缺乏资源来维持这么多的生命。即使科学家发明出替代资源，拥挤的人口也使我们不得不到其他星球寻找生存空间。但是目前太阳系还没有发现能维持生命的行星。因此和缺乏资源相比，缺乏生存空间才是最令人担忧、最难解决的问题。所以正确答案为C。

Passage 2
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 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 atmosphere
B．its atmosphere is the same as the earth's
C．there is a good supply of water on Venus
D．the days on Venus are long enough

答案：A
解析：
由第二段第一句中的“itwill be possible to change the atmosphere ofVenus and so create a new worl d”可知．so是表示因果的连接词，前因后果，所以正确答案A。

共用题干
第三篇

Preserve the Environment

Throughout history man has changed his physical environment in order to improve his way of life.
With the tools of technology he has altered many physical features of the earth.He has transformed
woodlands into farmland,and made lakes and reservoirs out of rivers for irrigation purposes or hydroelectric
power. Man has also modified the face of the earth by draining marshes and cutting through mountains to
build roads and railways.
However,man's changes to the physical environment have not always had beneficial results.Today,
pollution of the air and water is an increasing danger to the health of the planet.Each day thousands of tons
of gases come out of the exhausts of motor vehicles;smoke from factories pollutes the air of industrialized areas
and the surrounding areas of countryside.The air in cities is becoming increasingly unhealthy.
The pollution of water is equally harmful.In the sea,pollution from oil is increasing and is killing enor-
mous numbers of algae（水藻）,fish and birds.The whole ecological balance of the sea is being changed.
The same problem exists in rivers.Industrial wastes have already made many rivers lifeless.
Conservationists believe that it is now necessary for man to limit the growth of technology in order to sur-
vive on earth.

According to the passage,pollution of the air and water is caused by__________.
A:thousands of tons of gases coming out of the exhausts of motor vehicles
B:the changes of the environment that technology has brought to man
C:the increasing amount of oil that has been produced
D:industrial wastes discharged into rivers

答案：B
解析：
由文章第一段可知，人类改变自然环境是为了改善生活。故选D。
文章第二段提出人类使用技术工具改变了地球的自然面貌，为自己带来了便利。第三段说然而人类改变自然环境带来的不只是有利的一面。空气和水的污染已经威协到了植物的 健康生长。由此得知，空气和水的污染是由技术带给人类的环境的变化造成的。
由文章倒数第二段可知，随着石油开发对大海污染的加剧，大量的水藻．鱼类和鸟类被 杀死，由此造成海洋生态平衡的改变。故选C。
该题干问：最可能与环境保护者意见不一致的是？关于环境保护者的意见出现在文章 最后一段，"Conservationists believe that it is now necessary for man to limit the growth of technology in order to survive on earth"，可知环境保护者认为现在应该限制技术的发展速度以保证人类在 地球上生存下去。在四个选项中，A项Industrialists（工业家）与技术发展联系的最紧密，因此 最可能会不同意环境保护者的意见。C项Businessmen（商人）包括的范围很广，并不是所有的 商业活动都与技术发展有关。故选A。
从全文看，这篇文章的目的是：D项号召人们注意保护自然环境。第5部分：补全短文

共用题干
第三篇

Preserve the Environment

Throughout history man has changed his physical environment in order to improve his way of life.
With the tools of technology he has altered many physical features of the earth.He has transformed
woodlands into farmland,and made lakes and reservoirs out of rivers for irrigation purposes or hydroelectric
power. Man has also modified the face of the earth by draining marshes and cutting through mountains to
build roads and railways.
However,man's changes to the physical environment have not always had beneficial results.Today,
pollution of the air and water is an increasing danger to the health of the planet.Each day thousands of tons
of gases come out of the exhausts of motor vehicles;smoke from factories pollutes the air of industrialized areas
and the surrounding areas of countryside.The air in cities is becoming increasingly unhealthy.
The pollution of water is equally harmful.In the sea,pollution from oil is increasing and is killing enor-
mous numbers of algae（水藻）,fish and birds.The whole ecological balance of the sea is being changed.
The same problem exists in rivers.Industrial wastes have already made many rivers lifeless.
Conservationists believe that it is now necessary for man to limit the growth of technology in order to sur-
vive on earth.

Man has changed his physical environment with a view to_________.
A:altering the physical features of the earth
B:modifying the face of the planet
C:improving his surroundings'
D:bettering his way of life

答案：D
解析：
由文章第一段可知，人类改变自然环境是为了改善生活。故选D。
文章第二段提出人类使用技术工具改变了地球的自然面貌，为自己带来了便利。第三段说然而人类改变自然环境带来的不只是有利的一面。空气和水的污染已经威协到了植物的 健康生长。由此得知，空气和水的污染是由技术带给人类的环境的变化造成的。
由文章倒数第二段可知，随着石油开发对大海污染的加剧，大量的水藻．鱼类和鸟类被 杀死，由此造成海洋生态平衡的改变。故选C。
该题干问：最可能与环境保护者意见不一致的是？关于环境保护者的意见出现在文章 最后一段，"Conservationists believe that it is now necessary for man to limit the growth of technology in order to survive on earth"，可知环境保护者认为现在应该限制技术的发展速度以保证人类在 地球上生存下去。在四个选项中，A项Industrialists（工业家）与技术发展联系的最紧密，因此 最可能会不同意环境保护者的意见。C项Businessmen（商人）包括的范围很广，并不是所有的 商业活动都与技术发展有关。故选A。
从全文看，这篇文章的目的是：D项号召人们注意保护自然环境。第5部分：补全短文

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考题 共用题干 Early Ideas about the Universe1 Early man got his ideas about the universe by looking at the stars as you do.He observed carefully,and learned many things about the sun,the moon,and the stars.2 Suppose you were asked to collect evidence about the sun as early man did.You might go out morning after morning and see it come up in the east.Even on cloudy mornings,youwould observe that the darkness goes away and the world becomes light.You might not see the sun but would be sure it is there,because you notice that the earth warms up.As you continued,the sun climbs higher in the sky each day during part of the year. It stays in the sky longer. The earth gets warmer. Things begin to grow. It is spring and then summer.3 After a while the sun stays in the sky for shorter and shorter periods.Many plants begin to die.Leaves fall.Winter comes.Year after year this is repeated and you cannot tell exactly why it happens.But you realize that the sun seems to make the difference. Primitive（原始的）man felt that since the sun was so powerful it must be a god. It may seem silly to us now to worship（崇拜）a sun-god, but primitive man was right about the importance of the sun to life on earth.4 You have been told that the world is round.But suppose no one had ever taught you that the world was like a huge ball.Would you have ever thought of it yourself?You cannot see the curve（曲线）of the earth at once. You would have no idea of how big it was. That's why early man believed that the earth was small and flat.Such ideas appeared from the evidence they had.5 If you watch the stars night after night,you will see them rise and set.As you look at the sky,it is not difficult to imagine that you are in the center of a vast collection of twinkling（闪烁）lights. Some early astronomers（天文学家）believed the sky was a crystal shell or series of crystal shells,one inside the other. They believed this because that is what the night sky looked like.For many centuries,men believed that the earth was the center of the universe and that the sun,the moon,and the stars circled around it.Early man thought the earth was small and flat because_________.A:he did not observe the sun carefully enoughB:he could not see its curveC:the sun,the moon and the stars seemed to move around itD:the earth circles around the sunE:it looked like that at nightF:it has power over life on earth答案：B解析：
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考题 共用题干 第二篇Human and the EarthIn terms of the evolution of life on Earth,human beings have just arrived.Despite their shori time on Earth,however,people have brought about enormous changes to the surface of the planet一changes far out of proportion to the interval of time they have occupied it.People have more control over their surroundings than any other species on Earth.With the combination of intelligence and manual skill(allowing us to make and use tools),people have found ways to use plant and animal resources,mineral ores,fuels,and many other materials and resources from the Earth.As the number of people on Earth increases,it becomes increasingly difficult for the population to survive on the resources of the land.The amount of land is limited.Although agricultural production can be increased by use of machinery such as tractors and the addition of fertilizer,the land ultimately can produce only so much food and no more.As the human population grows,people consume more.Clearly,some locations on Earth already have too many people;in many of these areas,future increases will surely bring about more poverty and suffering. Yet people in rich nations use proportionally far more of the available resources than people in poorer nations.As they consume these resources without restraint,they also waste large amounts of them.People are only a very small fraction of all the living things on the planet.Yet their numbers create a drain on resources that can't be renewed.For example,the amount of water on Earth is limited,this water is cleaned through natural processes.However,the natural processes for filtering water can clean only a certain amount of water by removing the pollution.Likewise,a limited amount of petroleum can be found under the Earth's surface.Petroleum is a valuable resource.Should people use it up to manufacture petrol for automobiles?As people work to control the planet and make life comfortable,are they using up resources that are needed for their survival?What makes people feel hard to live on Earth?A:Fertilizer. B:Lse of machinery.C:Limited land. D:Limited mineral resources.答案：C解析：文章第一段第一句话提到“就地球上生命的进化而言，人类是姗姗来迟者”，因此比较而言，人类的历史并不长。选项A是正确的。从文章第二段第二句话“With the combination of intelligence and manual skill...”我们知道选项A和B都是正确的，因此选择D项。文章第三段提到，土地的总量是有限的。虽然使用拖拉机等机械和施用化肥可以提高农业产量，但是土地最终所能产出的粮食只有那么多，不会再增加。因此只有选项C是正确的。文章第四段第三句说富裕国家的人们所使用的能源在比例上远远大于贫穷国家的人们。选项C中提到的“发达国家的人们”最符合题意。根据文章最后一段关于资源的描述我们可以发现选项A、B、C都是正确的，只有选项D的表述错误，因此选择D项。
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考题 共用题干 第二篇Human and the EarthIn terms of the evolution of life on Earth,human beings have just arrived.Despite their shori time on Earth,however,people have brought about enormous changes to the surface of the planet一changes far out of proportion to the interval of time they have occupied it.People have more control over their surroundings than any other species on Earth.With the combination of intelligence and manual skill(allowing us to make and use tools),people have found ways to use plant and animal resources,mineral ores,fuels,and many other materials and resources from the Earth.As the number of people on Earth increases,it becomes increasingly difficult for the population to survive on the resources of the land.The amount of land is limited.Although agricultural production can be increased by use of machinery such as tractors and the addition of fertilizer,the land ultimately can produce only so much food and no more.As the human population grows,people consume more.Clearly,some locations on Earth already have too many people;in many of these areas,future increases will surely bring about more poverty and suffering. Yet people in rich nations use proportionally far more of the available resources than people in poorer nations.As they consume these resources without restraint,they also waste large amounts of them.People are only a very small fraction of all the living things on the planet.Yet their numbers create a drain on resources that can't be renewed.For example,the amount of water on Earth is limited,this water is cleaned through natural processes.However,the natural processes for filtering water can clean only a certain amount of water by removing the pollution.Likewise,a limited amount of petroleum can be found under the Earth's surface.Petroleum is a valuable resource.Should people use it up to manufacture petrol for automobiles?As people work to control the planet and make life comfortable,are they using up resources that are needed for their survival?Who use more available resources according to the passage?A:Rich people on Earth. B:Poor people on Earth.C:People in developed countries. D:People in developing countries.答案：C解析：文章第一段第一句话提到“就地球上生命的进化而言，人类是姗姗来迟者”，因此比较而言，人类的历史并不长。选项A是正确的。从文章第二段第二句话“With the combination of intelligence and manual skill...”我们知道选项A和B都是正确的，因此选择D项。文章第三段提到，土地的总量是有限的。虽然使用拖拉机等机械和施用化肥可以提高农业产量，但是土地最终所能产出的粮食只有那么多，不会再增加。因此只有选项C是正确的。文章第四段第三句说富裕国家的人们所使用的能源在比例上远远大于贫穷国家的人们。选项C中提到的“发达国家的人们”最符合题意。根据文章最后一段关于资源的描述我们可以发现选项A、B、C都是正确的，只有选项D的表述错误，因此选择D项。
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考题 共用题干 Where Did the Earth's Water Come From?Earth is located within the"snow line"of the solar system,the region closest to the Sun where H2 0 is primarily in liquid or gaseous form,if at all.______(46)The snow line phenomena is reflected in the water content of planets like Mercury,Venus,and Mars. Water is absent on Mercury.On Venus,H2O only exists as a trace element in the atmosphere.Mars only has a thin veneer of ice in its polar regions.In general,water is rare within the snow line.Why does Earth have so much water relative to the other inner planets?71%of the surface is covered in the oceans,more than half of which is deeper than 3,000 meters,with an approximate total volume of 1.3 billion cu km.______(47)There are various theories as to where all the Earth's water came from,but several theories have fared better than the others.______(48)When the Earth was in the process of forming,with a radius just 40%smaller than at present,it would have had enough gravity to hold on to a tenuous atmosphere with water vapor. The first water vapor on the planet would have come from the planet's internals,where volatile(low weight)chemicals would have a tendency to float to the top,and heavy chemicals(iron and nickel)would sink.Though the first of Earth's water came about through volcanism,this alone probably didn't produce enough to form stable pools on the surface.______(49)Comparing the isotope ratios of water on Earth and water from comets and asteroids has revealed that the majority of the Earth's water comes from asteroids.Throughout its history,Earth's water has increased in volume due to biological processes. In the early seas of Earth,hydrogen sulfide would have been in great supply,which,when reacted with carbon dioxide from the atmosphere during photosynthesis in sulfide-reducing bacteria,would have produced hydrogen,sulfur,and water.______(50)________（49）A: More water was added to the planet during several hypothesized large impacts from asteroids from the outer asteroid belt.B:We know that the oceans existed as early as 100 million years after the formation of the Earth.C:Still,the oceans only make up 0.023%of the Earth's total mass.D:Astronomers say Earth s water may have come from space.E:The snow line is located in the outerasteroid belt,between the orbits of Mars and Jupiter. F: Many geologists believe that the majority of Earth's water generated through this process.答案：A解析：文中第一段第一句提到了snow line，接下来的依据肯定还是要对snow line进行进一步说明，而选项中，只有E选项提到了snow line，所以选择E。文中第二段主要说明地球上的水占的比重，而只有C选项是对这一主题进行说明，所以选择C。根据后一句When the Earth was in the process of forming可以得知，该段是在讲述地球的形成历史，B选项We know that the oceans existed as early as 100 million years after the formation of the Earth也是在讲述地球形成的历史，所以选择B。后一句：Comparing the isotope ratios of water on Earth and water from comets and asteroids has revealed that the majority of the Earth's water comes from asteroids．通过把地球上水的同位素和小行星以及彗星上的水的同位素进行比较，发现地球上的水主要来自小行星。可以推断出，该句要讲述地球上的水与太空中小行星的关系，所以A选项正确。文中的最后一段主要是讲地球上水的来源。前一句：In the early seas of Earth,hydrogen sulfide would have been in great supply,which,when reacted with carbon dioxide from the atmosphere during photosynthesis in sulfide-reducing bacteria,would have produced hydrogen , sulfur , and water．在地球早期的海洋中，硫氢化合物非常丰富，在去硫细菌的光合作用的影响下，它与大气层中的二氧化碳产生化学反应，产生大量的氢、硫，以及水。这是地球自身产生的水，而F选项Many geologists believe that the majority of Earth's water generated through this process(许多地理学家认为地球上水的产生主要通过这一进程实现）正好承接前一句，所以F选项正确。
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考题 Uranus, ________ is much more massive than the Earth, seems to have been tipped over so that it lies on its side.A.what B.who C.that D.winch答案：D解析：本题考查的是定语从句中关系代词的选择。定语从句中没有what 引导词，what是引导名词性从句的; 先行词是人的时候用who，是物的时候用which或that; 题目意为“天王星，比地球大得多，似乎已经倾斜，使它位于它的一边。”先行词是物，且该句子是非限定性定语从句，因此选D。
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考题 共用题干 Early Ideas about the Universe1 Early man got his ideas about the universe by looking at the stars as you do.He observed carefully,and learned many things about the sun,the moon,and the stars.2 Suppose you were asked to collect evidence about the sun as early man did.You might go out morning after morning and see it come up in the east.Even on cloudy mornings,youwould observe that the darkness goes away and the world becomes light.You might not see the sun but would be sure it is there,because you notice that the earth warms up.As you continued,the sun climbs higher in the sky each day during part of the year. It stays in the sky longer. The earth gets warmer. Things begin to grow. It is spring and then summer.3 After a while the sun stays in the sky for shorter and shorter periods.Many plants begin to die.Leaves fall.Winter comes.Year after year this is repeated and you cannot tell exactly why it happens.But you realize that the sun seems to make the difference. Primitive（原始的）man felt that since the sun was so powerful it must be a god. It may seem silly to us now to worship（崇拜）a sun-god, but primitive man was right about the importance of the sun to life on earth.4 You have been told that the world is round.But suppose no one had ever taught you that the world was like a huge ball.Would you have ever thought of it yourself?You cannot see the curve（曲线）of the earth at once. You would have no idea of how big it was. That's why early man believed that the earth was small and flat.Such ideas appeared from the evidence they had.5 If you watch the stars night after night,you will see them rise and set.As you look at the sky,it is not difficult to imagine that you are in the center of a vast collection of twinkling（闪烁）lights. Some early astronomers（天文学家）believed the sky was a crystal shell or series of crystal shells,one inside the other. They believed this because that is what the night sky looked like.For many centuries,men believed that the earth was the center of the universe and that the sun,the moon,and the stars circled around it.Early astronomers believed that the sky was a crystal shell or series of crystal shells because_________.A:he did not observe the sun carefully enoughB:he could not see its curveC:the sun,the moon and the stars seemed to move around itD:the earth circles around the sunE:it looked like that at nightF:it has power over life on earth答案：E解析：
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考题 共用题干 So Many"Earths"The Milky Way（银河）contains billions of Earth-sized planets that could support life.That's the finding of a new study.It draws on data that came from NASA's top planet-hunting telescope.A mechanical failure recently put that Kepler space telescope out of service.Kepler had played a big role in creating a census of planets orbiting some 170,000 stars.Its data have been helping astronomers predict how common planets are in our galaxy.The telescope focused on hunting planets that might have conditions similar to those on Earth.The authors of a study,published in The Proceedings of the National Academy of Sciences,conclude that between 14 and 30 out of every 100 stars,with a mass and temperature similar to the Sun,may host a planet that could support life as we know it.Such a planet would have a diameter at least as large as Earth's,but no more than twice that big.The planet also would have to orbit in a star's habitable zone.That's where the surface temperature would allow any water to exist as a liquid.The new estimate of how many planets might fit these conditions comes from studying more than 42,000 stars and identifying suitable worlds orbiting them.The scientists used those numbers to extrapolate（推算） to the rest of the stars that the telescope could not see.The estimate is rough,the authors admit.If applied to the solar system,it would define as habitable a zone starting as close to the Sun as Venus and running to as far away as Mars.Neither planet is Earthlike (although either might have been in the distant past).Using tighter limits,the researchers estimate that between 4 and 8 out of every 100 sunlike stars could host an Earth-sized world.These are ones that would take 200 to 400 days to complete a yearly orbit.Four out of every 100 sunlike stars doesn't sound like a big number.It would mean,however,that the Milky Way could host more than a billion Earth-sized planets with a chance for life.The Kepler space telescope has been in service for 15 years.A:Right B:Wrong C:Not mentioned答案：C解析：本篇文章只在第二段第一句表明，近来一次机械故障使开普勒太空望远镜不再为我们服务，并没有提到开普勒太空望远镜为我们服务了多少年。第二段最后一句表明，开普勒太空望远镜主要寻找与地球有相似环境的星球。第三段第二句表明，可让生命存在的星球的直径至少与地球的直径一样大，但不会超过地球直径的两倍。由此可推测出其不会比地球小，因此题干表述错误。第三段第三、四句表明，适合生命存在的星球必须与它所环绕的恒星有一个合适的距离，以保证星球表面的温度允许液态水存在，而地球正是适合人类居住的星球，而且地球是绕着太阳运行的。第四段第一句表明，这项新评估源于对超过4.2万颗星球的分析，而非源于对17万颗星球的分析。第五段第一句表明，研究者承认这项评估是粗糙的，即不精确的。文章第一段指出，这次的调查结果是新的发现，但通篇文章并未提到这是对可能有生命存在的星球的首次研究。
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