must have done 和 must do 有什么区别!哪一个是表示对过去的猜测呢?有人说must后面接动词原形是对现在的猜测!

问题描述:

must have done 和 must do 有什么区别!哪一个是表示对过去的猜测呢?
有人说must后面接动词原形是对现在的猜测!

must have done sth: 一定做过某事。
must do sth: 必须作某事。

must have done是对过去的猜测.

表示对过去的猜测:must have done: 肯定已经做了什么事。 the cat must have eaten the fish. 猫一定已经把鱼吃了。
must do : 必须作某事。 i must finish my homework tonight. 今晚我必须完成家庭作业。

nust have done对现在的猜测
must do表示必须做某事,没猜测之意

must have done表示对过去的猜测
must do对现在的猜测

must have done 是虚拟语气,就是你说的对过去的猜测

我知道啊