单选题
What led to the conversation? A. A recent local storm. B. A recent radio program. C. A course the speakers are taking. D. Research being done by one of the speakers.
【正确答案】
A
【答案解析】[解析] W: Did you hear the thunder last night? M: Did I? It was really loud. W: I didn' t see any lightning, though. I thought that thunder and lightning always occur at the same time. M: They do. It' s no possible to have one without the other since thunder is a direct result of lightning. W: Really? M: Yes. Thunder is caused by the rapid expansion and contraction of highly heated air along the path of an electrical discharge. W: In other words, lightning quickly heats the air and causes thunder. But if the lightning is there, why can't we see it? M: Because it sometimes occurs very high in the clouds. W: I wonder if it' s possible to see the lightning and not to hear the thunder. M: Yes. It' s possible if the lightning flashes far enough away. Sound doesn' t travel as far as light.
单选题
Where does thunder occur? A. Where cool air hits mountains. B. Where lightning occurs. C. Near electrical wires. D. Underneath the clouds.
【正确答案】
B
【答案解析】
单选题
Why is lightning sometimes NOT seen during a thunder storm? A. It doesn't always occur. B. It is too faint to seen. C. It happens in a distant city. D. It is concealed by clouds.