单选题 There are some objects in the sky that move so quickly that sometimes you only see them out of the corner of your eye. These are some of the huge number of bits of rock and dust that are floating around in space, called meteoroids. Normally, we cannot see them at all, but if they travel too close to the Earth, they get caught by the pull of the Earth, and begin to fall towards us. They fall faster and faster, until they hit our atmosphere (大气层), by which time they are going so fast that they begin to burn up, and all that you see is a flash of light that moves very quickly across the sky and disappears. These shooting stars, or meteors as they are properly called, are quite common, and sometimes you may see several in a night.
Most meteoroids are very small bits indeed, and they bum up long before they get to the Earth. However, a very few do manage to get all the way through the atmosphere, and actually fall to the ground. Usually they do not do much damage, although this is not always the case.
Meteoroids that actually manage to reach the Earth are called {{U}}meteorites{{/U}}. Most countries have places where meteorites have struck the Earth. Some of these places are very large indeed and are tourist attractions.

单选题 Why do some objects from outer space fall to the ground?

A. They are too big.
B. They are hit by huge rocks.
C. They move too fast.
D. They are pulled by the Earth.

【正确答案】 D

【答案解析】[解析] 细节题。题干意为“为什么外太空的一些物体会掉落到地面?”根据文章第一段第三句“Normally, we cannot see them at all, but if they travel too close to the Earth, they get caught by the pull of the Earth, and begin to fall towards us.”可知，作者认为通常我们根本看不见它们，但是如果它们太靠近地球，它们就会被地球引力吸住，开始向我们掉落，故D正确。

单选题 What do we know about meteors from the text?

A. They become a star in the sky.
B. They are too small to be seen.
C. They disappear very quickly.
D. They do damage to the Earth.

【正确答案】 C

【答案解析】[解析] 细节题。题干意为“从文中我们对流星有哪些了解?”从文章第一段第四句话可知，那时它们的速度如此之快以至于它们开始燃烧，你所能看到的只是一道光划过天空，然后消失不见。由此推出，流星消失得非常快，故C正确。

单选题 What happens to most meteoroids coming into the atmosphere?

A. They burn up.
B. They fall to earth.
C. They explode.
D. The float in the air.

【正确答案】 A

【答案解析】[解析] 推理题。题干意为“大部分流星在穿过大气层时会发生什么?”由文章第一段可知，那时它们的速度如此之快以至于它们开始燃烧，你所能看到的只是一道光划过天空，然后消失不见。由此推出，流星穿过大气层时会燃烧，故A正确。

单选题 The word "meteorites" (Line 1, Para. 3) refers to pieces of rock that ______.

A. move fast in outer space
B. have been found at a tourist centre
C. flash through space at a high speed
D. have fallen onto the Earth from space

【正确答案】 D

【答案解析】[解析] 细节题。题干意为“‘meteorites’(第三段第一行)是指那些______的石头碎片。”根据本文第三段第一句话“Meteoroids that actually manage to reach the Earth are called meteorites.”可知，真的到达地面的流星被称为陨石，故D正确。