[单项选择]

Passage Four
Scientists have always wanted to know more about the other worlds in space. Years ago they knew a lot about the moon. They knew how big it is and how far away it is from the earth. But they wanted to know more about it. They thought and thought. At last they found the only way to know more was to send men to the moon.
The moon is about 384 000 kilometers away from the earth. A plane can not fly to the moon because the air reaches only 240 kilometers high above the earth. Then there is no air. But something can fly even when there is no air. That is’ a rocket (火箭).
Rockets can fly out into space. Rockets with men in them have already reached the moon. Some rockets without men in them have flown to other parts, much farther away from the earth than the moon in the universe. One day, rockets may be able to go to any place.

The moon is （　） away from the earth.
A. about 384 000 kilometers
B. 240 000 kilometers
C. only 348 000 kilometers
D. about 384 000 meters

[单项选择]

Passage Four
Scientists have always wanted to know more about the other worlds in space. Years ago they knew a lot about the moon. They knew how big it is and how far away it is from the earth. But they wanted to know more about it. They thought and thought. At last they found the only way to know more was to send men to the moon.
The moon is about 384 000 kilometers away from the earth. A plane can not fly to the moon because the air reaches only 240 kilometers high above the earth. Then there is no air. But something can fly even when there is no air. That is’ a rocket (火箭).
Rockets can fly out into space. Rockets with men in them have already reached the moon. Some rockets without men in them have flown to other parts, much farther away from the earth than the moon in the universe. One day, rockets may be able to go to any place.

The moon is （） away from the earth.
A. about 384 000 kilometers
B. 240 000 kilometers
C. only 348 000 kilometers
D. about 384 000 meters

[单项选择]The passage probably implies that scientists have been______.

[单项选择]According to the passage, scientists have positively confirmed that the brains of narcoleptics differ from those of normal brains in which of the following ways


A. Narcoleptic brains tend to remove degenerative tissue at a more prolific rate than that of nonnarcoleptics.
B. Narcoleptics are less responsive to drugs which treat neural autoimmune dysfunction than are nonnarcoleptics.
C. Nonnarcoleptics do not possess the same neurological immune antigens as narcoleptics.
D. Neurons that control muscle tone are damaged in the brains of narcoleptics, but not in those of non-narcoleptics.
E. (E) Narcoleptics experience greater neural degeneration as a result of aging than do nonnarcoleptics.

[单项选择]According to the passage, scientists have decided that sulfur aerosols from volcanic eruptions affect global temperatures to a greater extent than ash clouds because


A. the greenhouse gas effect produced by human activities tends to have a much greater environmental effect than that of volcanic explosions
B. clouds of sulfur-rich gases tend to achieve greater heights in the stratosphere than do ash clouds
C. a particular explosion producing high sulfur and little ash had a greater environmental effect than the converse
D. the burning of fossil fuels tends to exacerbate the effects of sulfurous aerosols, but not those of ash clouds
E. (E) global warming effects tend to minimize the impact of ash clouds, but not those of sulfurous aerosols

[单项选择]The old librarian always wanted people to study in her library.

[单项选择]

Passage Five
Scientists claim that air pollution causes a decline in the world’ s average air temperature. In order to prove that theory, ecologists have turned to historical data in relation to especially huge volcanic eruptions. They suspect that volcanoes effect weather changes that are similar to air pollution.
One source of information is the effect of the eruption of Tambora, a volcano in Sumbawa, the Dutch East Indies ( the former name of the Republic of Indonesia) ,in April 1815. The largest recorded volcanic eruption, Tambora threw 150 million ton of fine ash into the stratosphere. The ash from a volcano spreads worldwide in a few days and remains in the air for years. Its effect is to turn in coming solar radiation into space and thus cool the earth. For example, records of weather in Eng land show that between April and November 1815, the average temperature had fallen 4.5°F during the next twenty-four months, England suffered one of th
A. there was a long interval between cause and effect
B. the weather was difficult for us to forecast
C. weather forecasts were inaccurate
D. ecologists didn't exist until modem times