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About one million years ago,the Ice Age began.The Ice Age was a long period of time in which four great glaciers(冰川) pushed southward to cover almost all the upper half of North America,and then melted away.Each glacier was a thick sheet of ice and snow that spread out from a center near what is now Hudson Bay in Canada.The winters were long,and the cool summers were too short to melt much of the ice and snow.The ever?growing sheet built up to a thickness of two miles at its center.
As all glaciers do,these great glaciers slid(滑动). They pushed down giant trees in their paths and scraped(刮削)the earth bare(光秃秃)of soil.Many animals moved farther south to escape.Others stayed and were destroyed.
When winters of little snow came,the summer suns into the edges to the ice sheets.As the glaciers melted,rocks,soil and other things that had mixed with the ice and snow were left.New hills,lakes and rivers were formed.
The last of the great glaciers began its melting about 11 000 years ago.Itsmelting formed the Great Lakes.These lakes are today little changed from their early sizes the glaciers.This is the Mississippi Missouri Ohio system.These rivers were miles wide at first.Through the years they settle into their present channels.
The main idea of this passage is ________ .
A.the Ice Age was a long period of time
B.great glaciers covered North America many years ago
C.changes in climate helped to melt the glaciers
D.how glaciers changed North America
2.The author states that all glaciers ________.
A.are two miles thick B.form frozen lakes
C.are a million years old D.move and slide
3.From the information in this passage we know that ________.
A.glaciers are destructive
B.all glaciers in the world move southward
C.the Mississippi Missouri Ohio systems is larger than it was before the Ice Age
D.the Great Lakes are now smaller than they were before the Ice Age
4.The Ice Age lasted almost ____.
A.1 000 years B.100 years C.1 000 000 years D.11 000 years
5.In the last sentence,the word “their” refers to ________ .
A.lakes B.rivers C.glaciers D.systems
查看习题详情和答案>>Move Earth – it’s no science fiction
LONDON – Scientists have found an unusual way to prevent our planet from overheating: move it to a cooler spot. All you have to do is send a few comets (彗星) in the direction of Earth, and its orbit will be changed. Our world will then be sent spinning into a safer, colder part of the solar system.
This idea for improving our climate comes from a group of US National Aeronautics and Space Administration(NASA)engineers and American astronomers. They say their plan could add another six billion years to the useful lifetime of our planet—effectively doubling its working life.
The plan put forward by Dr Laughlin, and his colleagues Don Korycansky and Fred Adams ,needs carefully directing a comet or asteroid so that it passes close by our planet and sends some of its gravitational energy to Earth.
“Earth’s orbital speed would increase as a result and we would move to a higher orbit away from the Sun,” Laughlin said.
Engineers would then direct their comet so that it passed close to Jupiter or Saturn. The comet would pick up energy from one of these giant planets. Later its orbit would bring it back to Earth, and the process would be repeated. In the short term, the plan provides an ideal way to global warming, although the team was actually concerned with a much greater danger. The sun is certain to heat up in about a billion years and so “seriously compromise” our biosphere(生物圈)— by cooking us.
That’s why the group decided to try to save Earth.
The plan has one or two worrying aspects, however. For a start, space engineers would have to be very careful about how they directed their asteroid or comet towards Earth. The smallest miscalculation(误算)in orbit could fire it straight at Earth—with deadly consequences.
There is also the question of the Moon. As the current issue of Scientific American magazine points out, if Earth was pushed out of its current position it is “most likely the Moon would be stripped away from Earth,” it states. This would greatly change our planet’s climate.
What makes the scientists plan to move Earth?
A.A few comets are moving to the direction of Earth.
B.Earth’s working life is coming to an end soon.
C.Earth will become too hot for mankind to keep alive.
D.The moon is moving farther and farther away from Earth.
If the plan is successful, Earth will have a working life of ______years.
A.12 billion B.6 billion C.18 billion D.24 billion
What serious problems might the plan cause according to the passage?
A.The comet might hit Earth and man might lose the moon.
B.Earth might be moved too far away and man might be frozen to death.
C.The comet might hit Jupiter or Saturn and never return to Earth.
D.Earth’s working life might be greatly shortened.
What does the underlined word “compromise” mean?
A.provide B.benefit C.share D.endanger
查看习题详情和答案>>Move Earth—it’s no science fiction
LONDON-Scientists have found an unusual way to prevent our planet from overheating: move it to a cooler spot. All you have to do is send a few comets(彗星)in the direction of Earth, and its orbit will be changed. Our world will then be sent spinning into a safer, colder part of the solar system.
This idea for improving our climate comes from a group of US National Aeronautics and Space Administration(NASA) engineers and American astronomers. They say their plan could add another six billion years to the useful lifetime of our planet—effectively doubling its working life.
The plan put forward by Dr Laughlin, and his colleagues Don Korycansky and Fred Adams
,needs carefully directing a comet or asteroid so that it passes close by our planet and sends some of its gravitational energy to Earth.
“Earth’s orbital speed would increase as a result and we would move to a higher orbit away from the Sun,”Laughlin said.
Engineers would then direct their comet so that it passed close to Jupiter or Saturn. The comet would pick up energy from one of these giant planets. Later its orbit would bring it back to Earth, and the process would be repeated.
In the short term, the plan provides an ideal way to global warming, although the team was actually concerned with a much greater danger. The sun is certain to heat up in about a billion years and so “seriously compromise” our biosphere(生物圈)—by cooking us.
That’s why the group decided to try to save Earth.
The plan has one or two worrying aspects, however. For a start, space engineers would have to be very careful about how they directed their asteroid or comet towards Earth. The smallest miscalculation(误算)in orbit could fire it straight at Earth—with deadly consequences.
There is also the question of the Moon. As the current issue of Scientific American magazine points out, if Earth was pushed out of its current position it is “most likely the Moon would be stripped away from Earth,” it states. This would greatly change our planet’s climate.
1. What makes the scientists plan to move Earth?
A. A few comets are moving to the direction of Earth.
B. Earth’s working life is coming to an end soon.
C. Earth will become too hot for mankind to keep alive.
D. The moon is moving farther and farther away from Earth.
2.If the plan is successful, Earth will have a working life of ______years.
A.12 billion B.6 billion C.18 billion D.24 billion
3.What serious problems might the plan cause according to the passage?
A. The comet might hit Earth and man might lose the moon.
B. Earth might be moved too far away and man might be frozen to death.
C. The comet might hit Jupiter or Saturn and never return to Earth.
D. Earth’s working life might be greatly shortened.
4.What does the underlined word “compromise” mean?
A. provide B. benefit C. share D. endanger
5.Which of the following best shows how the plan would work?
查看习题详情和答案>>About ten years ago when I was an undergraduate in college. I was working as a practice student at my University's Museum of Natural History. One day while working at the cash register in the gift shop, I saw an elderly couple come in with a little girl in a wheelchair.
As I looked closer at this girl, I saw that she was kind of set on her chair. I then realized she had no arms or legs, just a head, neck and main body. She was wearing a little white dress with red dots.
As the couple wheeled her up to me, I was looking down at the register. I turned my head toward the girl and gave her a wink(眨眼). As I took the money from her grandparents, I looked back at the girl, who was giving me the cutest(可爱的), largest smile I have ever seen.
All of a sudden her handicap (残疾)was gone and all I saw was this beautiful girl, whose smile just melted me and gave me a completely new sense of what life is all about. She took me from a poor, unhappy college student and brought me into her world--- a world of smiles, love and warmth.
That was ten years ago. I'm a successful business person now and whenever I feel down and think about the troubles of the world, I think about that little girl and the remarkable lesson about life that she taught me.
What do we know about the author?
A.He graduated from Natural History University.
B. He majored in Natural History at university .
C.He ran a gift shop in the university
D.He is a successful businessman
When the author looked again, he saw that the little girl____.
A. was wearing a beautiful red dress
B.wasn’t able to move in the wheelchair
C.was badly injured
D.was only able to smile
In the author’s opinion, the little girl was not disabled at all because ______.
A.she told everyone how to live a good life
B.she offered him suppport in his business
C.she could take good care of herself
D.she had a strong spirit
What would be the best title for his passage?
A.World of smiles B.Love of a girl
C. A badly disabled girl D.Secret of a businessman
查看习题详情和答案>>Move Earth — it’s no science fiction
LONDON — Scientists have found an unusual way to prevent our planet from overheating: move it to a cooler spot. All you have to do is send a few comets(彗星)in the direction of Earth, and its orbit will be changed. Our world will then be sent spinning into a safer, colder part of the solar system.
This idea for improving our climate comes from a group of US National Aeronautics and Space Administration(NASA) engineers and American astronomers. They say their plan could add another six billion years to the useful lifetime of our planet—effectively doubling its working life.
The plan put forward by Dr Laughlin, and his colleagues Don Korycansky and Fred Adams ,needs carefully directing a comet or asteroid so that it passes close by our planet and sends some of its gravitational energy to Earth.
“Earth’s orbital speed would increase as a result and we would move to a higher orbit away from the Sun,” Laughlin said.
Engineers would then direct their comet so that it passed close to Jupiter or Saturn. The comet would pick up energy from one of these giant planets. Later its orbit would bring it back to Earth, and the process would be repeated. In the short term, the plan provides an ideal way to global warming, although the team was actually concerned with a much greater danger. The sun is certain to heat up in about a billion years and so “seriously compromise” our biosphere(生物圈)— by cooking us.
That’s why the group decided to try to save Earth.
The plan has one or two worrying aspects, however. For a start, space engineers would have to be very careful about how they directed their asteroid or comet towards Earth. The smallest miscalculation(误算)in orbit could fire it straight at Earth—with deadly consequences.
There is also the question of the Moon. As the current issue of Scientific American magazine points out, if Earth was pushed out of its current position it is “most likely the Moon would be stripped away from Earth,” it states. This would greatly change our planet’s climate.
What makes the scientists plan to move Earth?
A. A few comets are moving to the direction of Earth.
B. Earth’s working life is coming to an end soon.
C. Earth will become too hot for mankind to keep alive.
D. The moon is moving farther and farther away from Earth.
If the plan is successful, Earth will have a working life of ______years.
A.12 billion B.6 billion C.18 billion D.24 billion
What serious problems might the plan cause according to the passage?
A. The comet might hit Earth and man might lose the moon.
B. Earth might be moved too far away and man might be frozen to death.
C. The comet might hit Jupiter or Saturn and never return to Earth.
D. Earth’s working life might be greatly shortened.
What does the underlined word “compromise” mean?
A. provide B. benefit C. share D. endanger
Which of the following best shows how the plan would work?
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