【正确答案】 B

【答案解析】[听力原文]
Scientists say that nighttime flights are much more damaging to the environment than daytime air travel. In new research published in journal Nature, they say vapor trails produced by aircrafts do far more damage during the night. The reason is condensation water vapor emitted from hot engine of aircraft condensing into trailing clouds. Our science reporter M. G. has more. "The scientists say that in daylight the trails act like mini-clouds. They are good for the environment because the white color deflects the Sun"s rays and reduces temperature. At night from the sun goes down this positive benefit is lost. The impact of night travel is surprisingly large. In the United Kingdom only a quarter of flight takes place in darkness. But this accounts for up to 80% of greenhouse effect from condensation."

What is the main topic of this news?

[解析] 选项均为概括性较强的名词短语或句子表明，本题可能考查新闻的主旨。新闻开头提到，科学家们称夜间飞行对环境造成的危害要大于日间航行，接着举例说明夜间航行给环境带来的危害，故答案为B。

【正确答案】 C

【答案解析】[听力原文]
Why is the night flight more harmful?

[解析] 选项均为以because开头的句子表明，本题可能考查某事发生的原因。新闻中提到，夜间飞行的影响大得惊人，接着谈及在英国只有1/4的飞行是在夜间，但80%的温室效应却来自飞机的凝结液，故答案为C。