The professor paused as if ___________ his students to ask questions on the point he had just made.

A．expecting

B．is expecting

C．expected

D．to have expected

．下列说法中正确 （     ）

A．家庭电路中的熔丝熔断，一定是发生了短路

B．有金属外壳的家用电器，为了安全一定要插在三孔插座上

C．家用电能表上的示数显示了家庭用电的总功率

D．电扇工作时，消耗的电能全部转化为机械能