我们把经过电离层反射到地面的电波叫作（）。A.天波 B.地波 C.

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问题单项选择题

我们把经过电离层反射到地面的电波叫作（）。

A.天波

B.地波

C.地面波

D.表面波

答案

参考答案：A

单项选择题

A．He thinks that the things at sales are not good.

B．He thinks that the things at sales are of good quality.

C．He thinks that the things at sales are sometimes good.

D．He thinks that the things at sales are reasonable.

问答题简答题

什么是PRA？