1、表示推測的情態動詞 一. 表推測的情態動詞有： 肯定的推測一般用must，should/ought to, may/might或could(不用can) 1.must的語氣最強，譯為“肯定， 準 是，想必是”；(mustnt 表示禁止） 2.should/ought to 的語氣次之，譯為 “很可能, 應該”,指按常理推測； 3.may/might,could的語氣最弱，譯為 “也許，可能”。 4.cant /couldnt 表示否定推測, 不可 能eg. You have been working hard all day ,you must be tired. He must be wor

2、king in the office now. He should come here today. Can this be done by him? She may be still waiting for us. This may not be done by him. This can not be done by him. 二.“情態動詞+have done” 的用法。 1.must have done “過去一定做了某事” 表示對過去的一種肯定性推測。 eg. She must have gone by bus. It must have rained last night, for

3、 the road is quite muddy.2. can/could havedone“過去可能做了某事”， “could havedone”也可表示過去本可以做某事但實際上卻沒有做” eg. He was not at home last night, he could have gone to the cinema. I could have finished my homework last night, but I was too sleepy.3. “can/could not have done”“過去 不可能做了某事” 她不可能去你家，她不知道你的地址。 eg. She c

4、an not have been to your house；she does not know your address.4. may/might have done“過去或許做過某事” may/might not have done “過去或許 沒有做過某事” eg. I cant find my key, I might have left it at home. He might not have got your letter. 5.ought to/should have done,”表示本應該做某事，而事實上并沒有做”。 否定句表示“ 本不該做某事而實際上做了”。 你在實驗中本應該更仔細些的你在實驗中本應該更仔細些的 You ought to/should have been more careful in this experiment. 他不應該把那些舊衣服扔了。 He ought not to have thrown the old clothes away.6. “neednt have done”表示“本沒有 必要做某事實際上卻做了” 這次旅行我穿太多了，我本沒有必 要這樣做，天氣太熱了。 I