-----We did not see him at the lecture yesterday.

问题描述:

-----We did not see him at the lecture yesterday.
------You______him,since I went to an international conference with him,
B.can't have seen C.couldn't see
can't have done/shouldn't have done/mustn't have

can't have done/shouldn't have done都是对过去的虚拟,不能用mustn't have done表示对过去的猜测can't have done是过去不可能做shouldn't have done是本不应该做,但是已经做了选B是因为这是对过去的猜测.第二个人说...