【正确答案】
B
【答案解析】[听力原文]26-28
Would the world really be so much better off if there were no dust? (26) 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. (27) 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. (28) 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.
26. Would the world really be so much better off if there were no dust?
根据四个选项可推测问题可能询问“Yes/No”。本题关键句为“The answer is in some ways, yes, in some ways, no.”答案可以是肯定的，也可以是否定的。故选项B)为正确答案。
【正确答案】
C
【答案解析】[听力原文]
What would happen if there were no dust?
根据四个选项中都有would，可推测问题询问“可能会……”。本题关键句为“The lovely colors...is present in the air.”黎明时分天空中缤纷色彩主要是由空中存在的大量灰尘所生成的。“Sunsets are red, ...disappear from view.”落日是红色的，是因为这些灰尘颗粒折射了阳光中的红色射线。因此可知如果没有灰尘日升日落就失去了美丽。故正确答案为C)。