【正确答案】 C

【答案解析】[听力原文]30-32
We only have a few minutes left so I'd like to go over a couple of points before we move on.
Remember, although there are both horizontal and Vertical movements of air, the term "wind" is applied only to horizontal movements, and more air is involved in horizontal movements than those vertical movements. And what causes these horizontal movements? Ultimately, it's the solar radiation, because the unequal heating of the earth rather than the atmosphere produces horizontal differences in air pressure. These differences set winds in motion. Essentially, winds are the nature's way of balancing uneven distribution of air pressure over the earth. Secondly, let me repeat my answer to the question we had before about wind direction. Many people get confused by what they hear in weather forecast.
We talk about wind direction in terms of where the wind's coming from, not where it's blowing to. There is a good reason to this. To weather broadcasters, the origin of winds is more important than its destination. The winds' origin helps them predict the weather.
Logically, in the northern hemisphere, a north wind tends to bring cold weather, and the south wind warm weather. I haven't forgotten vertical movements of air. We don't have time today to talk about them in depth. In our next class then. I'll begin by discussing updraft and downdraft and how they affect the weather.
I suspect most of you can guess which of the two brings warm weather, and which brings cold.
30．According to the speaker，how's the term“wind” defined?

[解析] 题干中的is…defined对应文中的 is applied only to，由其后的horizontal movements，and more air is involved in horizontal movements than those vertical movements可知选项[C]为答案。

【正确答案】 A

【答案解析】[听力原文]
Why does the speaker mention solar radiation?

[解析] 短文中提到，And what causes these horizontal movements? Ultimately，it's the solar radiation，because…。由此可见，说话人之所以提到太阳辐射(solar radiation)是因为其是引起风的根本原因(ultimate cause)，选项[A]为答案。

【正确答案】 D

【答案解析】[听力原文]
What will the speaker probably discuss in the next class?

[解析] 短文末尾提到，I haven't forgotten vertical movements of air．We don't have time today to talk about them in depth．In our next class then，I'll begin by discussing updraft and downdraft and how they affect the weather。综合这些信息可推知说话人下节课的讨论内容。 vertical air movement是updraft和downdraft的上义词，因此选项[D]How vertical air movement influences weather为本题答案。