Question

might have been 和 cound have been的区别

Answer 1

都是虚拟语气.但是使用的场景不同.

might have been 多用于猜测,比如：

He might have been to Beijing.他大概去过北京.

You might have said this before.（猜想）你也曾说过这些话.

could have been多用于原本可以（能力上可及）的事情却没有做.比如：

I could have caught up with you. 我本来可以来和你们聚会的(但却没有去).

I could have been upset.我本来应该不高兴的（但是没有）