16. ----It’s getting dark, but Mr. Johnson is still at his office.

----No surprise. Who else can _____ he does?

A．do less work than

B．work as hardly as

C．work as hard as

D．be working hardly like

有三相正弦交流电动势的交流电称为（）。

A.三相交流电

B.三相电流

C.三相电压