The whole family were sound asleep when the disaster_____.

A．had taken place

B．took place

C．is taking place

D．has taken place

外勤人员外出需要配备基于3G的移动监控设备，以下哪个是最佳选择（）

A.枪机

B.球机

C.单兵

D.硬盘录像机