can't have done与could't have done的区别

问题描述:

can't have done与could't have done的区别
我知道这两个都表示
过去不可能做过某事,但有什么区别啊?
两个都出现选哪个啊

couldn't 较 can't 委婉, 表示多半是由客观原因造成的不能做,而can't 的主观色彩相对浓一些.