该), might, could, ought to, used to（过去常常）, need（需要）, dare（竟敢），have to（不得不）
*dare, need 也可作一般（行为）动词 *情态动词一般用法的否定：
mustn’t 不准, 禁止，不要 can’t(couldn’t) 不会；不能； may (might) not 不可以;
needn’t 没必要 ( = don’t have to ) used not／usedn’t to或didn’t use to… 过去不… dare not 不敢 *情态动词推测用法
Must 一定，肯定 can’t (couldn’t) 不可能 Can/ could 可能 Can’t (couldn’t) 不可能
may/ might “可能，也许” May (might) not 也许不，可能不 *推断用法
should／ought to“按理应当，应该是； shouldn’t 不应该 ( = ought not to ) *情态动词＋have ＋done结构表示对过去动作的推测
must have done：对过去的肯定推测，译作“一定做了…”，只能用于肯定句中。其否定形式为can’t／couldn’t have done
e.g. It must have rained last night, for the road was quite muddy.
can/ could have done：对过去的可能性推测，译作“可能做了…”。只能用疑问句中。
e.g. Can／Could he have said it? 他可能说过那种话吗？
may / might have v-ed：对过去的可能性推测，译作“也许能，有可能。 e.g. It’s too late. I think he may have gone to bed.
*情态动词＋have＋过去分词结构表示轻微的责备和后悔 肯定：过去应该做而没有做； 否定：过去不该（不必）做而做了。
⑴ might／could＋have＋过去分词：“本来可以，早就应该”（只用于肯定句，
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且不能用may, can）
You could have told me you were going to be late !你应当早告诉我你会晚到的！
⑵ should（ought to）＋have＋过去分词：“本应”（没做）; should not（ought not to）＋have＋过去分词：“本不该”（做了）
You should not have handed in your composition yesterday morning.你本不应把作文交了。
You should have been here earlier.你应该早点来才对。
3. needn't＋have＋过去分词：“本不必，本不须”（need只用于否定句）（做
了） You needn't have woken her up. It's only six．你其实不必叫醒她。现在才六点。 注意：did not need to do 动作并没发生（没做） 例：I didn’t need to get up early, so I got up until 9 a.m. *八大注意点
1.在以could, might 表示征询对方意见或表示请求时，回答应相应使用can, may — Might I watch TV after supper? — Yes, you ________.
A. may B. must C. might D. can
2. May I / we …？这一类疑问句的肯定回答为Yes, please.或Certainly；否定回答为Please don’t.或No, you mustn’t. 例如：
“May we leave now?” “No, you mustn’t. You haven’t finished your home work yet.”
3. need I / we …？这一类疑问句的肯定回答为Yes, we must; 否定回答为needn’t
4. 在回答must引起的问题时，肯定must; 如果是否定的答复，不能用mustn’t，而要用needn’t或don’t have to 5. I wish to go home with you, may I?
6. Do help yourself to have fruit, won’t you/ will you? （表示一种委婉的请求） 7.Shall 用于第三人称，表示许可，允许
Let’s do this job, shall we? Let us do this job, will you?
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8. should 也表示惊讶的语气，
例如：I was shocked that she should have said such a thing to you.(她竟然对你说那样的话,…) *四大特殊结构
1.may/ might as well + 动词原形”意为“最好，满可以，倒不如”，相当于had better
You may as well do it at once.
2.may well + 动词原形”是一种常见的结构，意为“（完全）能，很可能” He may well be proud of his son. 他大可为儿子高兴。
3. cannot … too / enough 表示 “无论怎么……也不算过分”、“越……越好” You cannot be too careful. 4. had better 最好
You had better not wake me up when you come in. *两大类区别：
一、表示能力: can, be able to
be able to 能用于各种时态。can / could 只能表示现在或过去的能力 *was / were able to : “设法做成某事” ，相当于managed to do sth；succeeded in doing sth.
二、used to 和would 的区别
used to过去常常（但现在已无此习惯，would无此含义）
He used to drink beer, now he drinks wine.他过去喝啤酒，现在喝白酒。 would只能用来谈动作；used to用来谈动作或状态（可与be, live, like, stay等状态动词连用）：
He would get up early when he lived in the country.他住在乡下时总是早起。 We used to live in a small town.（不能用would） Be used to doing sth: 习惯于做某事
真题速练 1. You _____Jim anything about. It was none of his business. 2000
a. needn‘t have told b. needn’t tell c. mustn’t have told d. mustn’t tell
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2. He ______unwisely, but he was at least trying to do something helpful. 1999 a. may have acted b. must have acted c. should act d. would act 3. Mush as______, I couldn’t lend him the money because I simply didn’t have that much spare cash. 1999
a. I would have liked to b. I would like to have
c. I should have to like d. I should have liked to 4. You ______Mark anything. It was none of his business. 1998
a. needn’t have told b. needn’t tell c. mustn’t have told d. mustn’t tell 5. As it turned out to be a small house party, we _____so formally. 1996 a. need not have dressed up b. must not have dressed up c. did not need to dress up d. must not dress up 6. The meeting’s been cancelled. Ann _____ all that work. 1995
a. need to do b. need have c. needn’t have done d. needed not to do 7. “She must be in the dormitory now.” “No, she ____ be there. I saw her in the classroom a minute ago.” 1994
a. mustn’t b. can’t c. couldn’t d. wouldn’t 8. He _____ the 8:20 bus because he didn’t leave home till 8:25. 1994 a. couldn’t have caught b. ought to have caught
c. shouldn’t have caught d. must not have caught
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英语专业四级考试语法.doc
