对交流做半波整流是为了能够有利于检验近表面的缺陷
参考答案：对
It is in this laboratory ______ is run by Mr. Wu ______ the experiments are done.
A．which; that
B．that; which
C．where; that
D．that; where
无线网络的窄带微波主要用于无线广域网。( )
