题目内容
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______ that the earth was flat？
A．Used it to be thought
B．Did it used to be thought
C．Was it used to being thought
D．Does it used to be thought
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更多“______ that the earth was flat…”相关的问题
Where have men traveled in a spaceship？
A．To other planets.
B．To the moon.
C．Only on the earth.
A: What happened to the priceless works of art？ B: ______
A．They were destroyed in the earthquake.
B．The earthquake was destroying them.
C．They destroyed in the earthquake.
D．The earthquake destroyed them.
A．By recycling all the water.
B．By using very little.
C．By transporting plenty from Earth.
D．By controlling the humidity on board.
Whom was probably the wheel invented by？
A．A group of early hunters.
B．The first man on earth.
C．A great prehistoric thinker.
D．The man who made the first cart.
One of the causes of earthquake might be that ______.
A．it occurs in the center of the earth, so experts cannot tell when earthquakes will occur
B．there is rushing water in the center of the earth
C．solid rocks under the ground move and strain against each other, causing the earth's surface moving
D．there are other unknown causes
Why does the professor talk about Tuzo Wilson？
A．Wilson developed a warning system for earthquakes.
B．Wilson wrote an article that contradicted scientific law.
C．Wilson first proposed the theory of plate tectonics.
D．Wilson discovered sea floor spreading in the North Atlantic.
According to paragraph 4, the Earth system as a whole is a closed system because
A．the Earth receives no energy from outside the system boundary
B．the boundary of the Earth system is clearly defined
C．no mass crosses the system boundary, but some energy does
D．the Earth system uses energy from solar radiation to support life
The sentence "Our planet has shrunk" underlined in Paragraph 1 means that______.
A．the earth has become physically smaller
B．the more advanced ways of traveling has made the distance between countries shorter
C．the traditional concept of our planet has become out-of-date
D．modern means of communication has made it much easier for people to communicate with each other from different parts of the world
When man began to search the skies, he saw a lot of things. In the universe(宇宙),the earth seemed to be just a small bit of dust. It is only a small planet, and travels around the sum The sun together with its planets, travels in the Milky Way(银河), our galaxy(星系). The Milky Way has about thirty billion stars like our sun, and is one of about a hundred million galaxies in the universe
Because the space (空间)is so great, it is difficult to work out how far away a star is. Instead of kilometres, we have light-years. A light-year means how far light travels in one year. Our nearest neighbour galaxy is more than 9000,000 light-years away from the earth.
Man has known that ______.
A．the Milky Way is the only galaxy
B．other galaxies are near ours
C．the sun is a large star in the Milky Way
D．the earth is a small part of the universe
Unless we spend money to spot and prevent asteroids(小行星) now, one might crash into Earth and destroy life as we know it, say some scientists.
Asteroids are bigger versions of the meteoroids(流星)that race across the night sky. Most orbit the sun far from Earth and don't threaten us. But there are also thousands whose orbits put them on a collision course with Earth.
Buy $40 million worth of new telescopes right now. Then spend $10 million a year for the next 25 years to locate most of the space rocks. By the time we spot a fatal one, the scientists say, we'll have a way to change its course.
Some scientists favor pushing asteroids off course with nuclear weapons. But the cost wouldn't be cheap.
Is it worth it？ Two things experts consider when judging any risk are: 1) How likely the event is; and 2) How bad the consequences if the event occurs. Experts think an asteroid big enough to destroy lots of life might strike Earth once every 400,000 years. Sounds pretty rare-but if one did fall, it would be the end of the world. "If we don't take care of these big asteroids, they'll take care of us", says one scientist. "It's that simple".
The cure, though, might be worse than the disease. Do we really want fleets of nuclear weapons sitting around on Earth？ "The world has less to fear from doomsday(毁灭性的) rocks than from a great nuclear fleet set against them, "said a New York Times article.
What does the passage say about asteroids and meteoroids？
A．They are heavenly bodies different in composition.
B．They are heavenly bodies similar in nature.
C．There are more asteroids than meteoroids.
D．Asteroids are more mysterious than meteoroids.
Unless we spend money to spot and prevent asteroids(小行星) now, one might crash into Earth and destroy life as we know it, say some scientists.
Asteroids are bigger versions of the meteoroids(流星) that reace across the night sky. Most orbit the sun far from Earth and don't threaten us. But there are also thousands of asteroids whose orbits put them on a collision course with Earth.
Buy $ 50 million worth of now telescopes right now. Then spend $ 10 million a year for the next 25 years to locate most of the space rocks. By the time we spot a fatal one, the scientists say, we'll have a way to change its course.
Some scientists favor pushing asteroids off course with nuclear weapons. But the cost wouldn't be cheap.
Is it worth it？ Two things experts consider when judging any risk are: 1) How likely the event is; and 2) How bad the consequences if the event occurs. Experts think an asteroid big enough to destroy lots of life might strike Earth once every 500,000 years. Sounds pretty rare— but if one did fall, it would be the end of the world. "If we don't take care of these big asteroids, they'll take care of us," says one scientist. "It' s that simple."
The cure, though, might be worse than the disease. Do we really want fleets of nuclear weapons sitting around on Earth？ "The world has less to fear from doomsday(毁灭性) rocks than from a great nuclear fleet set against them," said a New York Times article.
What does the passage say about asteroids and meteoroids？
A．They are heavenly bodies different in composition.
B．They are heavenly bodies similar in nature.
C．There are more asteroids than meteoroids.
D．Asteroids are more mysterious than meteoroids.
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