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A、Formation of raindrops in the air. B、Formation of vapor water in the air. C、Development of air pollution. D、Increase of raindr
A、Formation of raindrops in the air. B、Formation of vapor water in the air. C、Development of air pollution. D、Increase of raindr
admin
2009-09-12
86
问题
Would the world really be so much better off if there were no dust? The answer is in some ways, yes, in some ways, no. What is dust anyway? It consists of particles of earth, or other solid matter, which are light enough to .be raised and carried by the wind. Where do these particles come from? They might come from dead plants and animal matter, from sea salt, from desert or volcano sand and from ashes. For the most part, dust is not a very desirable or beneficial thing. But in one way, it helps make the world more beautiful. The lovely colors of the dawn depend to a great extent on the amount of dust that is present in the air. Particles of dust in the upper air reflect the sun’s rays. This makes its light visible on earth an hour or two after sunset. But different colors which make up the sun light are bent .at different angles as they are reflected by the dust and water steam particles. Sunsets are red, because these particles bent the red rays of the sun in such a way that they are the last rays to disappear from view. Another useful function of dust has to do with ram. The vapor water in the air would not become a liquid very readily, if it did not have the dust particles serving as centers for each drop of water. Therefore, clouds, mist, fog and rain are largely formed of an infinite number of moisture particles of dust.
选项
A、Formation of raindrops in the air.
B、Formation of vapor water in the air.
C、Development of air pollution.
D、Increase of raindrops.
答案
A
解析
[听力原文]
What is another function of dust according to the speaker?
根据四个选项可推测问题可能询问某物的“作用”。本题关键句为“Another useful function of dust...centers for each drop of water.”灰尘的另一个功能和下雨有关。如果没有灰尘作为雨滴的核心,空气中的水蒸气不会很容易的变成液体落下。因此可知灰尘的另一个作用是成雨。故选项A)为正确答案。
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0
大学英语四级
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