--Has the train arrived yet?---No it ought to twenty minutes ago.A. arriveB. have arrive

问题补充：

--Has the train arrived yet?---No, it ought to twenty minutes ago.

A. arrive

B. have arrived

C. be arriving

D. be arrive

答案：

A. arrive

(答案→)B. have arrived

C. be arriving

D. be arrive

解析：ought to have done=should have done表示:本应该做却没有做.