语法——情态动词

题目

语法——情态动词
Research findings show we spend about two hours dreaming every night,no matter what we ____have done during the day.
横线上填may,请解释语法并翻译.
为什么不能用 could?

答案

may/might have done的意思是：可能做过某事,对发生的事的较不肯定的推测.例如：I haven't seen him for a long time.I am not sure what has happened to him.He might have gone abroad.could have done有两重意思...