答案：A

题目分析：考查情态动词+have done的用法：can't/ couldn't have done 根本不可能... needn't have done 本没必要,,,, must have done. 肯定已经.....(不要用mustn't have done.....) shouldn't have done 本不该......句意：昨天下午我妹妹在大剧院碰见了他，因此他肯定没有参加你的讲座。选A。

点评：Could have done sth本可以做某事；should have done本应该做某事，实际上却没有做；must have done一定做了某事。Might have done也许做某事。都是情态动词+have done的用法，平时要加强识记忆。