同学你好，该知识点来自沪江网校《英语零基础直达大学六级全能畅学卡【全额奖学金班】》的课程，想要更系统的学习，欢迎进入课程学习。不仅可以和更多的同学一起学习，而且还有老师、助教随时的学习指导和知识点解答哦。

同学你好~
must have done 对过去的推测，一定做了某事
He was subtilized someone must have entered his room.
他敏锐地察觉到一定有什么人进过他的房间。

must have been done对过去的推测，被动形式
This village must have been hit by hurricane, for we saw the ruined houses and the fallen trees all over the places.
这个村子一定是遭受了龙卷风的袭击，我们看到到处都是被破坏的房屋和被吹倒的树木。

must have been doing 对过去的肯定推测，一定正在做某事
He must have been hoping for a relaxed time. No such luck.
他一定是一直想放松一段时间，可就是没这个命。

祝同学学习进步~