Now that man has actually landed on the surface of the moon, he has learned many new things about it. But one thing man knew before he ever reached the moon was that there was no life on it.
There is no atmosphere (大气层) on the moon. The lack of air means that the moon is not protected from any of the sun’s rays. The sun sends out heat and light radiation (辐射). Life on earth depends on heat and light. But the sun also sends out dangerous kinds of radiation. The earth’s atmosphere protects us from most of them. On the moon, however, there is no atmosphere to stop the radiation. All the sun’s rays beat down on the surface of the moon.
Because there is no atmosphere, the moon’s surface is either extremely hot or extremely cold. As the moon circles around the earth, the side of it that is lighted up by the sun becomes very hot. The temperature there reaches more than 300 degrees Fahrenheit (华氏温度). This is hotter than boiling water. The hot lunar
A. Why is there no air on the moon
B. Why is there no life on the moon
C. Why is the moon hotter than the earth
D. Why is the moon colder than the South Pole
Now that man has actually landed on the surface of the moon, he has learned many new things about it. But one thing man knew before he ever reached the moon was that there was no life on it.
There is no atmosphere (大气层) on the moon. The lack of air means that the moon is not protected from any of the sun’s rays. The sun sends out heat and light radiation (辐射). Life on earth depends on heat and light. But the sun also sends out dangerous kinds of radiation. The earth’s atmosphere protects us from most of them. On the moon, however, there is no atmosphere to stop the radiation. All the sun’s rays beat down on the surface of the moon.
Because there is no atmosphere, the moon’s surface is either extremely hot or extremely cold. As the moon circles around the earth, the side of it that is lighted up by the sun becomes very hot. The temperature there reaches more than 300 degrees Fahrenheit (华氏温度). This is hotter than boiling water. The hot lunar
A. the sun
B. the moon
C. the earth
D. the planet
Man has been storing up useful knowledge about himself and the universe at the rate which has been spiraling upward for 10,000 years.
The (21) took a sharp upward leap with the invention of writing, but even (22) it remained painfully slow for several centuries. The next great leap forward (23) knowledge acquisition did not occur (24) the invention of movable type in the 15th century by Gutenberg and others. (25) to 1500, by the most optimistic (26) Europe was producing books at a rate of 1000 titles per year. This means that it (27) a full century to produce a library of 100,000 titles. By 1950, four and a half (28) later, the rate had accelerated so sharply that Europe was producing 120,000 titles a year. (29) once took a century now took only ten months. By 1960, a (30) decade later, the rate had made another significant jump, (31) a century’s work could be finished in seven
A. about
B. only
C. more than
D. less than
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