He hurried to the airport with his friends only ______ that all the film stars they liked best had been picked up by their company.

A． to tell

B．to be told

C． telling

D．told

常见的操作过电压有( )。

A．切除空载线路引起的过电压

B．切除空载变压器的过电压

C．电弧接地过电压

D．空载线路合闸时的过电压

E．电感性负载的拉闸过电压