________ cave that George has discovered in his lifetime is near the Alps.

A．The hundredth

B．The hundred

C．Hundredth

D．A hundredth

WXR中的磁控管振荡器（）。

A.在收发开关接通时可产生射频振荡信号

B.在负高压脉冲加至阴极时产生射频振荡

C.在正高压脉冲加至阳极时产生射频振荡

D.是由调制器中的磁性开关控制