21.7 情態(tài)動(dòng)詞 have 過去分詞 分類:英語(yǔ)學(xué)習(xí)1) may(might) have done sth,can (could) have done sth 表示過去,推測(cè)過去時(shí)間里可能發(fā)生的事情.
Philip may (might) have been hurt seriously in the car accident.
Philip can (could) have been hurt seriously in the car accident.
2) must have done sth,對(duì)過去時(shí)間里可能發(fā)生的事情的推測(cè),語(yǔ)氣較強(qiáng),具有"肯定","諒必"的意思.
---Linda has gone to work,but her bicycle is still here.
---She must have gone by bus.
3) ought to have done sth,should have done sth
本應(yīng)該做某事,而事實(shí)上并沒有做.否定句表示"不該做某事而做了".
You ought to (should) have been more careful in this experiment.
He ought not to have thrown the old clothes away.（事實(shí)上已扔了.）
ought to 在語(yǔ)氣上比should 要強(qiáng).
4) needn't have done sth 本沒必要做某事
I dressed very warmly for the trip,but I needn't have done so.The weather was hot.
5) would like to have done sth 本打算做某事
I would like to have read the article,but I was very busy then.
21.8 should 和ought to
should 和ought to 都為"應(yīng)該"的意思,可用于各種人稱.
---Ought he to go?
---Yes.I think he ought to.
表示要求,命令時(shí),語(yǔ)氣由 should（應(yīng)該）、had better最好）、must（必須）漸強(qiáng).
21.9 had better表示"最好"
had better 相當(dāng)于一個(gè)助動(dòng)詞,它只有一種形式,它后面要跟動(dòng)詞原形.
had better do sth
had better not do sth
It is pretty cold.You'd better put on my coat.
She'd better not play with the dog.
had better have done sth表示與事實(shí)相反的結(jié)果,意為"本來最好".
You had better have come earlier.