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.吗?谢谢
问题描述：
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.吗?
谢谢
答
不能换。第一个句子错误
答
大意上是没有什么区别的，但是用could可以显现出你说话的时态为过去，也是一种相对can更委婉的表达
答
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...