—Could you tell me_____________?

—Certainly.  In half an hour.

A. when the high speed train will arrive

B. when the high speed train arrived

C. if the high speed train has arrived

在（）时，应立即使用应急操舵。

A.自动操舵失灵

B.随动操舵失灵

C.主操舵装置发生故障

D.自动操舵和随动操舵系统发生故障