情态动词的用法归纳
1.must & need & have to
情态动词 | 含义 | 否定式 | 注意点 |
must | 表必要“必须” | needn’t “不必” | ( 区别 have to)有时表“偏要” |
表推测 “一定” | can’t“不可能” | 只能用于肯定句，不能用于否定、疑问句 |
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1) must 表示推测时， 只能用于肯定句。
must do 对一般时的肯定推测
must be doing 对现在的动作进行肯定推测
must have done 对过去发生的事情作出的肯定判断
e.g. 他们买了一辆新车。 他们一定很有钱
They have bought a new car. They must have a lot of money.
他现在一定在看小说He must be reading novels now.
路是湿的。昨天晚上一定下雨了。The road is wet. It must have rained last night.
2) need
1.作情态动词时,仅用于否定或疑问句,后接动词原形,表“需要”
You needn’t return the book now.
-- Need he start from the beginning?
--Yes,hemust. -- No, he needn’t/doesn’t have to.
2.needn’t have done 表示做了本不必要做的事情,意为“本不必要…”
Our color TV t is still good enough. You needn’t have bought a new one.
3.作实义动词时,表示“需要”，有人称、时态、和数的变化
He needs to finish it this evening.
The classroom needs cleaning.
4) 注意对need问句的回答:
--Need I finish the work today?
--Yes,you must.
No, you needn’t. /No, you don’t have to
needn’t 对其它情态动词的回答:
养字组词
--Shall I tell John about it?
--No, you needn’t
--No, you don’t have to
--Must we do it now?
--No, you needn’t
--No, you don’t have to
春节去哪里旅游2. can/could
情态动词 | 含义 | 否定式 | 注意点 |
can / could | 表能力“能/会” | can’t“不会，不能” | 区别 be able to |
表许可“可以” | can’t “不可以，不许” | 代替may |
表推测“可能” | can’t “不可能” | 主要用于否定/疑问句中 |
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1 表示某人通过努力克服困难做成某事,要用was / were able to.
2 could, might, would 表委婉语气用于疑问句, 答语仍须用can, may, will.
3 can 用于肯定句中, 可表示”有时可能”
4. can/could have done “本可以，本可能做某事” 用于肯定句中，表示对过去发生的事情做出的判断。
你本来可以考的更好。You could have had a better mark.
5. can/could not have done 对过去发生多条件查找行为进行推测:不可能做某事
1) 刚才我还看见他了， 所以他不可能出国的。
I saw him just now so he couldn’t have gone abroad.
2) 门是锁着的， 所以她不可能在家。
The door was locked，so she couldn’t have been at home.
3.may/might
情态动词 | 含义 | 否定式 | 注 意 点 |
may /might | 表许可“可以” | mustn’t “不许，严禁” | 口语中也可用can’t |
表推测“可能” | can’t “不可能” | 话题英文主要用于肯定句，不能用在疑问句（may not 可能不） |
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might/may have done,表示对过去发生的动作进行可能性推测，
1）他可能去医务室了。He may have gone to the clinic.总结报告模板
2）他可能已经从报纸上知道这个消息了。
He might have read about the news in the newspaper.
1. ---May I u your pencil?
---Yes, you may. / No, you mustn’t.
2. She may not be working now.
3. John might be at home now.
4. Helen may go on the trip with us, but she isn’t very sure yet.
5. She may / might have read it in the paper.
6. He may not have finished reading the book.
4.will/would
情态动词 | 用 法 |
will | 表请求(第二人称) | 表意志,意愿 | 表某种倾向或习惯 |
would | 更客气的请求 | 过去的意志（愿） | 过去的倾向或习惯 |
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5.shall ,should 和ought to
情态动词 | 用 法 |
shall | 征求对方意见(第一, 三人称) | 表示命令,警告, 威胁或允诺 (第二, 三人称) |
should / ought to | 表示劝告,建议尧山大峡谷漂流,命令或责任 “应该, 必须” | 表示推测, “理应, 估计, 大概, 可望” | should 还可表示“竟然” |
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1.在陈述句中,shall用于二、三人称表示允诺、警告、命令、决心等。
You shall do as I say. (命令)
Nothing shall stop me doing it. (决心)数学不好
Tell him that he shall have the book tomorrow. (允诺)
2.在疑问句中,用于一、三人称，用来表示请求或征求意见。
Shall I open the window for you？（征求意见）
Shall he fetch some water for you？（请求）
3. should常表示劝告、建议、命令，与ought to意义相近，但ought to多表示责任、义务，语气强烈。
Young people should learn how to u computers.
Every citizen ought to obey law.
You ought not to go.
4.should/ought to have done表示责备或批评,意为“本应该…但”,ought to的语气更强烈,用于否定则表示“本不该…但”
You should/ought to have told her the truth earlier.
She shouldn’t have left without saying a word.
5.Should用于可能性推测时,表“应该，很可能”
They left at 5:30. They should get there now.
六.可兼做行为动词的情态动词：need 、 dare
1.作为情态动词用，常用在否定句和疑问句中。
Dare (need) +S +V
S + daren’t (needn’t) +V
I daren’t walk through the forest at night.
Dare you walk through the forest at night?
You needn’t return the book now.
Need he go yesterday?
2.作实义动词用，常用在肯定句中, 有人称、时态、和数的变化
He needs to go there himlf.
He has grown up,so we don’t need to worry about him.
3.Sth (sb) need( want, request)+ doing/ to be done
The hou needs cleaning/ to be cleaned物联网的发展前景
The boy needs nding to the hospital at once.
表示推测——情态动词的重要用法
情态动词 对将来 对现在 对过去
肯定的推测 + V. + V. + have done
Must 常见must be + be doing
可能的推测 + V. + V. + have done
may, might + be doing
可以用not表示“可能不”
否定的推测 +V. + V. + have done
can’t,
couldn’t + be doing
