[originaltext] The winds of a tornado are the most violent and destructive o

游客2023-08-27  39

问题  
The winds of a tornado are the most violent and destructive ones on Earth. Any of you who have seen one knows very well how frightening and powerful they are. What’s interesting about them is that scientists don’t actually know exactly why tornadoes occur.
    We do know, however, what happens when tornadoes are formed. As you remember, a front occurs when cool, dry air from the north meets warm, humid air coming from the south. Where these air masses meet, a narrow zone of storm clouds develops, and thunderstorms, and sometimes tornadoes, occur.
    How is this violent weather produced? Well, a mass of warm, humid air rises very rapidly. As it rises, more warm air rushes in to replace it. This inrushing air also rises, and in some cases, especially when there is extreme thermal instability, begins to rotate. When this happens, the rotating air forms a tornado.
    Even if you’ve seen tornadoes only in movies, you know that they can destroy buildings in seconds. This is possible because when a tornado passes over a house, it sucks up air from around the house and so the air pressure outside the house drops rapidly. Inside, pressure remains the same. So, air pressure inside is greater than air pressure outside. The result is that the building explodes outward. Next, we’ll talk a little bit about how new technological developments are being used to try to predict tornadoes.
16. What does the speaker say about the scientists?
17. In what way does a narrow zone of storm clouds develop?
18. What will happen to a building when air pressure inside is greater than outside?

选项 A、Where dry and humid air masses meet.
B、Where the air becomes warm and humid.
C、When thunderstorms or tornadoes occur.
D、When the air rises very rapidly.

答案 A

解析 原文提及“当来自北方寒冷干燥的空气与来自南方温暖湿润的空气相遇,锋面形成。当这些气团相遇,一个狭窄的暴风云区也形成。”故A正确。
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