— What do you think of the Chinese language today?

— Quite popular. It _____ in communicating with other countries. More and more foreign friends are

     learning Chinese. [ ]

A. plays an important role

B. is playing an important role

C. has played an important role

D. is being played an important role

倒机电路故障时默认为主用的操表机是（）。

A.A操表机

B.B操表机

C.故障时主用操表机