“情態(tài)動詞+have done”結(jié)構(gòu)的用法是中學(xué)階段的重要語法項目。為了便于同學(xué)們學(xué)習(xí)，現(xiàn)將這種結(jié)構(gòu)的兩種主要用法列表歸納如下：
一、表示對過去情況的推測或估計
| 結(jié)構(gòu) | 所用的句式 | 意義 |
| must have done | 肯定句 | 一定（已經(jīng)）…… |
| may/ might have done | 肯定句 | 可能（已經(jīng)）…… |
| 否定句 | 可能還沒有…… | |
| can/ could have done | 否定句 | 不可能（已經(jīng)）…… |
| 疑問句 | 可能（已經(jīng)）……了嗎？ |
說明：1. might/ could有時并不是may/ can的過去式，而是表示一種委婉的語氣或更小的可能性。
2. might have done有時可用于疑問句中，此時might就相當(dāng)于can/ could。
二、表示對過去所發(fā)生的事情的遺憾或責(zé)備
| 結(jié)構(gòu) | 所用的句式 | 意義 |
| should/ ought to have done | 肯定句、否定句、疑問句 | 本來（不）應(yīng)該……的 |
| might/ could have done | 肯定句 | 本來能夠/可以……的 |
| need have done | 否定句 | 本不必要……的 |
說明：1. might have done有時可表示對過去發(fā)生事情的慶幸，意為“差點兒……”。如：
Didn’t you see that car nearly hit me? I might have been killed.
2. 要注意needn’t have done與didn’t need to do 意義的差別。如：
He needn’t have come. 他本沒有必要來。（實際卻來了）
He didn’t need to come. 他沒有必要來。（實際也沒來）
練習(xí)
1. —Do you know where David is? I couldn’t find him anywhere.
—Well, he _________ have gone far, for his coat is still here.
A. shouldn’t
B. mustn’t
C. can’t
D. wouldn’t
2. He ____________ you more help, even though he was busy.
A. might have given
B. might not give
C. may not have given
D. may give
3. There was plenty of time. She ___________.
A. mustn’t have hurried
B. couldn’t have hurried
C. mustn’t hurry
D. needn’t have hurried
4. —Tom graduated from college at a very young age.
—Oh, he ______ have been a very smart boy then.
A. could
B. should
C. might
D. must
5. My English-Chinese dictionary has disappeared. Who ______ have taken it?
A. should
B. must
C. could
D. shall
6. I really worried about you. You ________ home without a word.
A. mustn’t leave
B. shouldn’t have left
C. couldn’t have left
D. needn’t leave
Key: 1~6 CADDCB
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