Section ⅢGrammar - 情态动词＋have done的用法

　　语法图解

　　探究发现

　　①Many people think the monster may be a distant cousin of the Loch Ness monster in Scotland.

　　②They also think that there might be similar creatures in other lakes around the world.

　　③But in China, the idea of the dragon may have come from the alligator.

　　④You might have given your parents more help earlier.

　　⑤It must have rained last night, for the road was quite muddy.

　　⑥He can't have forgotten it, for he talked about it yesterday.

　　⑦You ought to/should have done the job more carefully.

　　⑧You oughtn't to/shouldn't have asked such a foolish question.

　　[我的发现]

　　(1)①②句表示可能性的推测，意为"可能，也许"。

　　(2)③④句表示对过去发生的事情的推测，意为"可能已经"。

　　(3)⑤句表示对过去事情的很有把握的肯定推测，意为"肯定做过某事"，而⑥句则表示对过去发生事情的有把握的否定推测，意为"不可能做过某事"。

　　(4)⑦句表示"过去本应该做却未做的事"，⑧句则表示"过去本不该发生却发生了的事"。

　　1．may/might have done sth.表示对过去行为的推测，意为"也许/或许已经做过某事"，might可能性更小，主要用于肯定句和否定句中。

John isn't at home. I think he may/might have gone to school.