My aunt here by now for she took the early bus.A. must arriveB. can arriveC. may arriveD

问题补充：

My aunt here by now, for she took the early bus.

A. must arrive

B. can arrive

C. may arrive

D. ought to have arrived

答案：

A. must arrive

B. can arrive

C. may arrive

(答案→)D. ought to have arrived

解析：ought to除了可以跟should一样表示“应该”之外，还可以表示推测，“照理应该”，而must表示相当肯定的语气，“一定；必定”，本题还着重考查正确使用时态，表示到目前应该已经发生用ought to +完成时态。