问题补充：
----- John looks a bit upset. Did you tell him the bad news?
------Yes, but I him after his birthday party.
A. should have told
B. must have told
C. shouldn’t have told
D. needn’t have told
答案：
(答案→)A. should have told
B. must have told
C. shouldn’t have told
D. needn’t have told
解析：考查虚拟语气。Should have done sth本应该做某事实际上却未坐；must have done一定做了某事；shouldn’t have done本不应该做某事，实际上却做了。Needn’t have done本不需要做某事，实际上却做了。句意—John看上去有点难过。你把那个坏消息告诉他了？—是的。可我本应该是在生日聚会以后在告诉他的。根据句意说明A正确。
