问题补充:
--- Have you told him we have changed the plan?
I have, but I haven’t done it yet.
A. must
B. ought to
C. needn’t
D. can’t
答案:
A. must
(答案→)B. ought to
C. needn’t
D. can’t
解析:考察情态动词用法。A必须,一定;B应该;C不必;D不可能;ought to have done本应该做某事,实际上却做未。Must have done一定做了某事;needn’t have done本不需要做某事,实际上却做了。句意:—你告诉他我们改变计划了吗?—我本应该告诉他,但是我还没有告诉他呢。根据句意说明B正确。