情态动词can'thavedone和couldn'thavedone有什么区别吗对过去发生的事情否定猜测用can'thavedone或couldn'thavedone,两者有区别吗?比如Hecan’thavegonetoBeijingforIsawhimaminuteago.能换成Hecouldn

Question

情态动词can't have done 和couldn't have done 有什么区别吗
对过去发生的事情否定猜测用can't have done 或couldn't have done ,两者有区别吗?
比如 He can’t have gone to Beijing for I saw him a minute ago.能换成He couldn’t have gone to Beijing for I saw him a minute ago.

Answer 1

can't have done（不可能做过）是must have done（一定做过）的否定形式.couldn't have done(可能没做过)是may have done(有可能做过)的否定形式.一般认为can't have done有80%以上的把握.而couldn't have done则委...