Official 43 Lec 4
答题结果:0/6
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Question 4 of 6
Why are sunrise and sunset the best times to listen to VLF signals?

A.

Because thunderstorms are most likely to occur then

B.

Because radio waves travel through natural waveguides then

C.

Because higher-frequency signals are less active then

D.

Because temperatures are not extremely high or low then

我的答案:

正确答案:B

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