—Mary broke up with me!
—You have forgotten about the Valentine's Day．
A. shouldn't
B. couldn't
C. needn't
D. mustn't
网友回答
(答案→)A. shouldn't
B. couldn't
C. needn't
D. mustn't
解析：考查情态动词用法。“情态动词+have done”既可以表示对过去情况的推测，也可以表示对过去所发生情况的虚拟。有一些固定搭配：Shouldn’t have done本不应该做某事，实际上却做了；couldn’t have done不可能做了某事；needn’t have done本不必做某事，实际上却做了；句意：—Mary和我分手了！—你本不应该忘记这个情人节的！根据句意说明A正确。