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

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问题     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 burn 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 meteorites. Most countries have places where meteorites have struck the Earth. Some of these places are very large indeed and are tourist attractions.
Why do some objects from outer space fall to the ground?

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

答案D

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 atall,but if they travel too close to the Earth,they get caught by thepull 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。
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