Question

It's no longer a question now _____ man can land on the moon.

A．when

B．that

C．whether

D．how

Answer 1

B

考查主语从句。本题的it是形式主语，真正的主语是that man can land on the moon,that引导起这个主语从句，在句中起连接作用，没有任何实际意义。