If he had started at nine oclock， he ought to have been in London by eleven oclock.

　　如果他在九点出发，那他十一点钟该到达伦敦了。

　　小升初英语语法零基础：may have done用法小结

　　may/might have done 推测过去

　　may/might+动词的完成式表示对过去发生的行为的推测。例如：

　　-Whatever has happened to George？

　　-乔治发生了什么事？

　　-I dont know. He may have got lost.

　　-我不知道，他可能迷路了。

　　You might have read about it in the papers.

　　你可能在报上已经看过这个消息了。

　　(之前我们做过can have done用法小结，can have done表推测时都是对过去进行推测，但是may have done不仅可以推测过去)

　　may/might have done 推测现在

　　may/might+动词的完成式表示对现在情况的推测。例如：