[英语角]情态动词

简介


四大分类



①只做情态动词:may, might, must..②可做情态动词又可做https://baike.so.com/doc/6731662-6945963.html :如:need, dare,can.......
③具有情态动词特征:have(had,has) to,used to, ought to④可做情态动词又可作https://baike.so.com/doc/5405125-5642896.html :如:shall(should),will(would)

注意



mustn't代表强烈禁止 must表示主观，have to表示客观。美式英语中常用must not 而不用 mustn't. mayn't,mightn't和shan't也很少用

常用



can (could), may (might), must, need, ought to, dare (dared), shall (should), will (would)

位置

1. 具有助动词作用，可以用来构成否定句，疑问句及用于简单回答。Can you sing English songs? 你会唱英语歌吗?Yes ,I can. 是的，我会。
2. 后接动词原形，接不带to的不定式。She may lose her way. 她可能迷路了。
3. 无人称和数的变化。We must stay here. 我们必须待在这儿。He must stay here. 他必须待在这儿。
4. 有一定的词义，但并不完整，必须与动词原形一起构成谓语。(后面加动词原形)
5. 在以Could引导的表示委婉语气的疑问句，常用来表示请求别人帮助或对长辈的请求的。如:(Could you come to my party on Saturday afternoon?)注意:这里不是情态动词的用法。回答为:肯定:Yes，I can./Sure./Certainly. 否定:Sorry,I am afraid not.(在作否定回答时，要注意:在拒绝长辈的请求时，不能用can not，这样显得语气太过生硬，不礼貌。但是在长辈拒绝晚辈的请求是可以用can not的。)

特点




情态动词无人称和数的变化，情态动词后面跟的动词须用原形，否定式构成是在情态动词后面加 "not"。个别情态动词有现在式和https://baike.so.com/doc/5963903-6176853.html 两种形式，过去式用来表达更加客气，https://baike.so.com/doc/6629221-6843022.html 的语气，时态性不强，可用于https://baike.so.com/doc/285227-301981.html ，https://baike.so.com/doc/6723836-6937973.html 或https://baike.so.com/doc/4860967-5078472.html 。情态动词属https://baike.so.com/doc/530699-561901.html ，故没有https://baike.so.com/doc/5409336-5647348.html 。He could be here soon. 他很快就来。
We can't carry the heavy box. 我们搬不动那箱子。I'm sorry I can't help you. 对不起，我帮不上你。
基本助动词与情态助动词最主要的区别之一是:基本助动词本身没有词义，而情态助动词则有自己的词义，能表示说话人对有关动作或状态的看法，或表示主观设想:What have you been doing since? (构成完成进行体，本身无词义)
你一直在干什么?I am afraid I must be going. (一定要)
恐怕我必须走了You may have read some account of the matter. (或许已经)
你可能已经读过关于这件事的一些报道除此之外，情态助动词还有如下词法和https://baike.so.com/doc/4853750-5070982.html 特征:

1. 除ought和used和have to以外，其他情态动词后面只能接不带to的不定式。如果我们把ought to和used to看做是固定词组的话，那么，所有情态动词无一例外地只能接不带to的不定式:We used to grow beautiful roses.我们过去常常种这种漂亮的玫瑰花I asked if he would come and repair my television set.我问他是否来修我的电视机
2. 情态助动词在限定动词词组总是位居第一:They need not have been punished so severely.他们不需要如此严厉的惩罚
3. https://baike.so.com/doc/2482374-2623528.html 用于第三人称单数现在式的时候，没有词形变化，即其词尾无-s形式:She dare not say what she thinks.她不敢说她是怎么想的
4. 情态动词没有非限定形式，即没有不定式和https://baike.so.com/doc/6623457-6837254.html 形式，也没有相应的https://baike.so.com/doc/5410261-5648342.html :Still,she needn't have run away.不过，她不必跑了
5. https://baike.so.com/doc/2482374-2623528.html 的"时"的形式并不是时间区别的主要标志。在不少场合，https://baike.so.com/doc/2482374-2623528.html 的现在时和过去时形式都可以表示现在、过去或将来时间:Would you mind very much if I ask you to do something?你会很介意如果我让你做什么?She told him he ought not to have done it.她告诉他他不应该这样做
6. 情态助动词之间是相互排斥的，即在一个限定动词词组中只能出现一个https://baike.so.com/doc/2482374-2623528.html ，但有时却可以与have和behttps://baike.so.com/doc/7527505-7801598.html 连用:You should have washed the wound.你应该已经洗好了伤口Well,you shouldn't be reading a novel.嗯，你不应该读一本小说
7. https://baike.so.com/doc/5398358-5635750.html musthttps://baike.so.com/doc/4922011-5141146.html 否定回答要用needn't而不是mustn't。Must I read books every day、我必须每天读书No,you needn't . 不，你不必

用法




首先它是https://baike.so.com/doc/2563740-2707510.html ，而且不同于行为动词，行为动词表示的是可以通过行为来表达的动作(如写，读，跑)，而情态动词只是表达的一种想法(如能，也许，敢)。用法是:情态动词+行为动词原形
例句:I can read this sentence in English.我能用英语读这句话。
情态动词是一种本身有一定的词义，表示说话人的情绪，态度或语气的动词，但不能单独作谓语，只能和其他动词原形构成谓语。We can be there on time tomorrow.我们明天能按时去那儿。
May I have your name? 我能知道你的名字吗?Shall we begin now?我们现在就开始吗?
You must obey the school rules.你必须遵守校规。情态动词数量不多，但用途广泛，主要有下列:
can (could),may (might),must,need,ought to,dare (dared),shall (should),will (would),have,had better.情态动词还有一个很重要的用法，即情态动词表推测--
用法小结(一)情态动词表推测的三种句式
1.在肯定句中一般用must (一定)，could(可能)，might /may(也许，或许)。e.g:(1)He must/can/may,might know the answer to this question.
他一定/可能/也许知道这个问题的答案。(2)It is cold in the room. They must have turned off the heating.
屋里很冷，他们肯定把暖气关了。2.否定句中用can't / couldn't(不可能)，may not/might not(可能不)。
e.g:(1)It can't/couldn't be the headmaster. He has gone to America.这不可能是校长，他去美国了。
(2)He may not/might not know the scientist.他也许不认识那位科学家。
3.疑问句中用can/could (能……?)。e.g:(1).Could he have finished the task?
他可能把任务完成了吗?(2).Can he be at home now?
他现在能在家吗?注:以上三种句式中情态动词的语气按程度都是依次递减的。Might,could并非may,can的过去式，而表示语气较为委婉或可能性较小。
(二)情态动词表推测的三种时态1.对将来情况的推测，用"情态动词 + https://baike.so.com/doc/6749840-6964394.html "。
e.g:(1).She must / may / might / could arrive before 5.5:00前她一定/可能/也许到。
(2).She must/may/might/could walk miles and miles among the hills without meeting anyone.她一定/可能/也许会在山里一连走好几英里而遇不到一个人。
2.对现在或一般情况的推测，用"情态动词 + be"，"情态动词 +be doing"或"情态动词 + https://baike.so.com/doc/6749840-6964394.html "。e.g:(1).He must / may / might / could be listening to the radio now.
他一定/可能/也许正在听收音机。(2).He can't ( couldn't ) / may ( might ) not be at home at this time.
这个时候他不可能/可能不在家。(3).Mr. Bush is on time for everything .How can ( could ) he be late for the opening ceremony
布什先生一向准时，这次开幕式他怎么可能迟到呢?3.对过去情况的推测，用"情态动词 + have +https://baike.so.com/doc/5963849-6176799.html "。
e.g:(1).It must / may / might / could have rained last night .The ground is wet.地湿了，昨晚肯定/可能/也许下雨了。
(2).The door was locked. He can ( could ) not / may ( might ) not have been at home .门锁着，他不可能/可能不在家。
(3).Can / Could he have gotten the book?难道他找到书了吗?
注:情态动词 should /ought to表推测时，意为"想必会，理应……"但与"have +https://baike.so.com/doc/5963849-6176799.html "连用时，则又可构成虚拟语气意为"本应该做某事却没做"。例如:(4).It's seven o'clock. Jack should/ought to be here at any moment.
现在七点钟了，杰克理应随时到达。(推测)(5).She should / ought to have attended your birthday party,but she had to look after her mother in hospital. (虚拟)
她本该出席你的生日晚会的，可是她得在医院照顾她妈妈。(6).Tom should not /ought not to have told me your secret,but he meant no harm. (虚拟)
汤姆本不该告诉我你的秘密，可是他并无恶意。can 和could 表 推测
对现在或将来的推测，两者均可用，但can 通常只用于https://baike.so.com/doc/5430808-5669093.html 或https://baike.so.com/doc/5414827-5652969.html 中，一般不用于https://baike.so.com/doc/6284431-6497902.html ，而could则可用于肯定句、否定句和疑问句;对过去的推测，应在 can,could 之后接动词的完成式，且此时can仍只用于否定句或疑问句，不用于肯定句;而could 则可用于各种句型。如:Can [Could] this be true? 这能是真的吗
Where can [could] he have gone? 他能到哪里去了呢She can't [couldn't] have left so soon. 她不可能走得这么早。
He could have gone home. 他可能已回家了。注:could后接动词的完成式，除表示对过去的推测外，还可表示过去没有实现的可能性(即某事本来可以发生，却没发生)，或委婉地责备某人过去应该做某事而没有去做(此时不用can)。如:
You could have started a little earlier. 你本可早点动身的。You needn't have cooked it. We could have eaten it raw. 你其实可以不煮熟(它)，我们(本来)可以生吃。
can 和could 表 允许表示现在的允许时，若是请求别人允许自己做某事，两者均可用，但用could 语气更委婉;若是自己允许别人做某事，一般只用 can，而不用 could。如:
Can [Could] I come in? 我可以进来吗"Could [Can] I use your pen? " "Yes,of course you can." "我可以借用你的钢笔吗?""当然可以。"(不能说Yes,you could.)
表示过去的允许时，若表示过去一般性允许(即表示某人随时都可以做某事)，用could;若表示在过去某一特定情况下允许进行某一特定的活动，则不用 could。如:When I lived at home,I could watch TV whenever I wanted to. 我住在家里时，想什么时候看电影就可以什么时候看。(一般性允许)
I was allowed to see the film yesterday evening. 昨天晚上允许我去看了电影。(特定的允许，不能用 could)can 和could 表 https://baike.so.com/doc/4507886-4717612.html
can 表示现在的能力，could 表示过去的能力，要表示将来具备的能力通常 be able to 的将来时态。其中要注意的是，could 表示过去的能力，通常只用于表示过去一般性能力，而不表示过去具体某次特定情形下能够做某事的能力。如:他学习很努力，所以考试能及格。
误:He studied hard and could pass the exam.正:He studied hard and was able to pass the exam.
注:若在否定句中没有以上限制，即couldn't 可表示过去特定情况下的能力，如可说 He studied hard but still couldn't pass the exam.口诀:情态动词两特点
动词原形接后面，说话语气较委婉。can "能力"may"许可"，must"责任"或"义务"。否定回答needn't换，"需要"need, dare"敢"。should"应该"，would"愿"，have to"被迫"表客观。

功能.
助动词(auxiliary)主要有两类:基本助动词(primary auxiliary)和情态助动词(modal auxiliary)。基本助动词有三个:do,have和be;情态助动词基本的有十四个:may,might; can,could; will,would; shall,should; must,need,dare,used to,ought to.had better 上述两类助动词的共同特征是，在协助主动词构成限定动词词组时，具有作用词的功能:

1) 构成否定式:

He didn't go and neither did she.他没去，她也没去。

The meeting might not start until 5 o'clock.会议可能直到五点才开始。

2) 构成疑问式或附加疑问式:

Must you leave right now?你一定要马上离开吗?

You have been learning French for 5 years,haven't you?你已经学了五年法语，不是吗?

3) 构成修辞倒装:

Nowhere can he obtain any information about his sister.他无处得到他姐姐的任何消息。

Hardly had he arrived when she started complaining.他刚到，她就开始抱怨起来。

4) 代替限定动词词组:

A: Who can solve this crossword puzzle?

B: Tom can.

A: Shall I write to him?

B: Yes,do.
•can和could

1. 表示能力或客观可能性，还可以表示请求和允许。如:

Can you finish this work tonight?你今晚能完成这项工作吗?

Man can not live without air.人离了空气不能活。

- Can I go now? - Yes,you can.

-我现在可以走了吗?-你可以。

注意:①could也可表示请求，语气委婉，主要用于疑问句，不可用于肯定句，答语应用can(即could不能用于现在时态的简略答语中)。如:

Could I come to see you tomorrow?我明天能来看您吗?

Yes,you can. (否定答语可用No,I'm afraid not.)

是的，你可以。(不，恐怕不行。)

②can表示能力时，还可用be able to代替。如:

I'll not be able to come this afternoon.

我今下午不能来。

2. 表示惊异、怀疑、不相信的态度。(主要用在否定句、疑问句或惊叹句中)

Can this be true?这可能是真的吗?

How can you be so careless!你怎么能这么粗心!

This can not be done by him.这不可能是他做的。

3. "can(could) + have + 过去分词"的疑问或否定形式表示对过去发生的行为怀疑或不肯定。如:

He can not have been to that town.他不可能去过那个镇。

Can he have got the book?他可能拥有这本书吗?

4. 用在疑问句及否定句中，表示惊讶，不相信等.

5. can not```too\enough表示"无论怎样``````也不过分","越``````越好"

6.can 可以表示体力或脑力方面的能力，能够，能，会

Can you finish the work in such a short time你能在那么短的时间内完成这项工作吗?

7. can 表示许可、允许 ， 在疑问句中表示要求，在否定句中表示不许，此时可以和may通用。
•may和might

1. 表示许可。

表示请求、允许时，might比may的语气更委婉一些，否定回答时(口语中常用) no,you can't . or,yes,please 用mustn't表示"不可以"、"禁止"、"阻止"之意(具有强烈禁止的意思)如:

You may drive the car.

你可以开这辆车。

- Might I use your pen? - No,you mustn't.

-我可以用你的钢笔吗?-不，绝对不行。

用May I ... 征询对方许可在文体上比较正式，在口气上比较客气。在日常口语中，用Can I ... 征询对方意见在现代口语中更为常见。

2. 用于祈使句中表示祝愿。如:

May you succeed! 祝你成功!

3. 表示推测、可能(疑问句不能用于此意)。

He may be very busy now. 他现在可能非常忙。

4. "may(might) + have + 过去分词"表示对过去发生的行为的推测。如:

He may not have finished the work. 他可能没有完成工作。
•must

1. 表示必须、必要。(must表示主观多一些而have to则表示客观多一些)如:

I have to give up smoking.(可能是由于身体或其它原因等不得不戒烟)

I must give up smoking. (自己觉得有必要戒烟)

You must come in time. 你必须及时过来。

回答must引出的问句时，如果是否定的回答，不能用mustn't，而要用needn't或don't have to。

- Must we hand in our exercise books today?

- Yes,you must. (No,you don't have to.)

-我们今天必须交上练习册吗?

-是的。(不，不必。)

mustn't意思为"不许、不准"，表示禁止。

-You mustn't play football in the stree

2. "must be + 表语"的结构表示推测，它的否定或疑问式用can代替must。

This must be your pen. 这一定是你的钢笔。

3. "must + have + 过去分词"的结构常用在肯定句中，表示对过去发生的行为的推测。它的否定或疑问式用can代替must。

He must have been to Shanghai. 他一定去过上海。

have to

4. have to的含义与must相似，两者往往可以互换使用，但have to有各种形式，随have的变化而定。must与have to有下列几点不同:

① must表示的是说话人的主观看法，而have to则往往强调客观需要。如:

The play is not interesting. I really must go now.这部剧没意思。我真的必须现在就走。

I had to work when I was your age.当我像你这么大时，我不得不工作。

② must一般只表现在一般现在时，have则有更多的时态形式。

③ 二者的否定意义不大相同。如:

You mustn't go. 你可不要去。

You don't have to go. 你不必去。

④ 询问对方的意愿时应用must。如:

Must I clean all the room?我一定要打扫整个房间吗?

注意:have to也可拼做have got to。

5. 表示一种与说话人 愿望相反、不耐烦的感情色彩，偏偏、非要。

Why must you always bother me为什么你总是来烦我?

6. must可以表示"非要，偏要"

Must you open the window? It's so cold outside.你非要/偏要开窗吗?外面真的很冷。
•dare和need

1. need表示"需要"或"必须"，作情态动词时，仅用于否定句或疑问句中，在肯定句中一般用must,have to,ought to，或should代替。如:

You needn't come so early.

- Need I finish the work today?

- Yes,you must.

注意:needn't + 不定式的完成式"表示本来不必做某事而实际上做了某事"。如:

You needn't have waited for me.

2. Dare作情态动词时，主要用于疑问句、否定句和条件从句中，一般不用在肯定句中。如:

How dare you say I'm unfair.

He daren't speak English before such a crowd,dare he?

3. Dare和need常用作实义动词，有时态、人称和数的变化，所不同的是，作实义动词时，在肯定句中，dare后面通常接带to的不定式，在否定和疑问句中，dare后面可接带to或不带to的不定式。如:

I dare to swim across this river.

He does not dare (to) answer.

Don't you dare (to) touch it!

I wondered he dare (to) say that.

He needs to finish it this evening.
•shall

一.Shall的用法:
1.Shall用于第一人称，表示征求对方的意愿。如:What shall we do this evening?
2.Shall用于第一、第三人称疑问句中，表示说话人征求对方的意见或向对方请示。如:Shall we begin our lesson?When shall he be able to leave the hospital?
3.Shall用于第二、第三人称，表示说话人给对方命令、警告、允诺或威胁。如:You shall fail if you don't work harder. (警告)He shall have the book when I finish reading. (允诺)He shall be punished. (威胁)
•should

二.Should的用法:

1. Should表示义务、责任、劝告、建议，其同义词是ought to;在疑问句中，通常用should代替ought to。如:

You should go to class right away.

Should I open the window?

Should的含义较多，用法较活，现介绍三种其特殊用法。请看下面的句子:

① I should think it would be better to try it again. 我倒是认为最好再试一试。

② You are mistaken,I should say. 依我看，你是搞错了。

③ I should advise you not to do that. 我倒是劝你别这样做。

④ This is something I should have liked to ask you. 这是我本来想问你的。

从以上例句可以看出:情态动词should用于第一人称时可以表示说话人的一种谦逊、客气、委婉的语气。

Should还可以用在if引导的条件从句，表示一件事听起来可能性很小，但也不是完全没有可能。相当于"万一"的意思。从句谓语由should加动词原形构成，主句谓语却不一定用虚拟语气。如:

⑤ Ask her to ring me up if you should see her. 你万一见到她，请让她给我打个电话。

⑥ If you should change your mind,please let us know. 万一你改变主意，请通知我们。

⑦ Should I (If I should) be free tomorrow I will come. 万一我明天有时间，我就来。

此外，Why(or How) + should结构表示说话人对某事不能理解，感到意外、惊异等意思。意为"竟会"。如:

⑧ Why should you be so late today? 你几天怎么来得这么晚?

⑨ - Where is Betty living? - 贝蒂住在哪里?

- How should I know? - 我怎么会知道呢?

⑩ I don't know why you should think that I did it. 我真不知道你凭什么认为这件事是我干的。

2. "should + have + 过去分词"结构一般表示义务，表示应该做到而实际上没有做到，并包含一种埋怨、责备的口气。如:She should have finished it.

I should have helped her,but I never could.

You should have started earlier.

3.表示规章制度，用should
•will和would

1. 表示请求、建议等，would比will委婉客气。如:

Would you pass me the book?

2. 表示意志、愿望和决心。如:

I will never do that again.

They asked if we would do that again.

3. 用"will be"和"will(would) + have + 过去分词"的结构表示推测，主要用于第二、三人称。前者表示对目前情况的推测，后者表示对已经完成的动作或事态的推测。如:

This will be the book you want.

He will have arrived by now.

The guests would have arrived by that time.

I thought you would have finished this by now.

4.will表示习惯、请求，固有性质等。

Everyday he will sit here hour after hour doing nothing.(习惯)

Will you help me with my English?(请求)

The door won't open. (固有性质)

5.Would可表示过去反复发生的动作或某种倾向。Would表过去习惯时比used to正式，并没有"现已无此习惯"的含义。如:

The wound would not heal.

During the vacation he would visit me every week。

6. 表料想或猜想。如:

It would be about ten when he left home.

What would she be doing there?

I thought he would have told you all about it.
•ought to

1. Ought to表示应该。如:

You ought to take care of him.

2. 表示推测。注意与must表示推测时的区别:

He must be at home by now. (断定他已到家)

He ought to be home by now. (不十分肯定)

This is where the oil must be. (比较直率)

This is where the oil ought to be. (比较含蓄)

3. "ought to + have + 过去分词"表示过去应做某事而实际未做。如:

You ought to have asked him (but you didn't).

这时，ought to和should可以互相换用。

注意:在美国英语中，ought to用于否定句和疑问句时，to可以省略。如:

Ought you smoke so much?

You oughtn't smoke so much.

ought和should的区别:

1.ought语气略强。

2.should较常用。

3.ought在美国英语中用的很少，而should却相当常用。

4.ought属正式用语。

注:由于ought to 没有过去式，所以在直接引语变间接引语的过程中，就不再变化.

used to，had better，would rather的用法

1. Used to表示过去的习惯动作或状态，现在已不存在，在间接引语中，其形式可不变。如:

He told us he used to play football when he was young.

在疑问句、否定句、否定疑问句或强调句中，可有两种形式:

疑问句

Did you use to go to the same school as your brother?

Used you to go to the same school as your brother?

否定句

I usedn't to go there.

I didn't use to go there.

Usedn't 亦可拼作usen't，但发音皆为['ju:snt]。

否定疑问句

Usen't you to be interested in the theatre?

Didn't you use to be interested in the theatre?

强调句

I certainly used to smoke,but it was a long time ago.

I certainly did use to smoke,but it was a long time ago.

其反意疑问句或简略回答中，也有两种形式:

She used to be very fat,didn't she? (口语+常用)/ use(d)n't she? (正式+过时)

Did you use to play chess? Yes,I did.

Used you to get up early in the morning? Yes,I did. (Yes,I used to.)

2. Had better意为"最好"，后接不带to的不定式。如:

- We had better go now.

- Yes,we had (we'd better / we had better).

Hadn't we better stop now? (Had we better not stop now?)

I think I'd better be going. (用于进行时态，表"最好立即")

You had better have done that. (用于完成时态，表未完成动作)

注:①had best与had better同意，但较少用。②You had better … 用于同辈或小辈，对长辈不可用。

3. Would rather意为"宁愿"，表选择，后接不带to的不定式。如:

I'd rather not say anything.

Would you rather work on a farm?

- Wouldn't you rather stay here?

- No,I would not. I'd rather go there.

由于would rather表选择，因而后可接than。如:

I would rather work on a farm than in a factory.

I would rather watch TV than go to see the film.

I would rather lose a dozen cherry trees than that you should tell me one lie.

I'd rather you didn't talk about this to anyone. (句中的'd rather不是情态动词，would在此是表愿望的实义动词)

注:由于used to，had better同ought to一样没有过去式，所以在直接引语变间接引语的过程中，也不再变化.

can (could),may (might)的用法

can (could) 表示说话人能，可以，同意，准许，以及客观条件许可，could 为 can 的过去式。

Can you pass me the books?你能给我递一下书吗?

Could you help me,please?请问，你能帮助我吗?

What can you do?你能干点什么呢?

Can you be sure?你有把握吗?

can 和could 只能用于现在式和过去式两种时态，将来时态用 be able to 来表示。

He could help us at all.他完全可以帮助我们。

With the teacher's help,I shall be able to speak English correctly.由于老师的帮助，我将能准确地讲英语。

may (might) 可以，表示说话人同意，许可或请求对方许可。

You may take the book home.你可以把书带回家去.

May I come in?我可以进来吗?

May I use your dictionary?我可以用你的词典吗?

You may put on more clothes.你可以多穿点衣服.

He said he might lend us some money.他说他可以借给我们一些钱。

may 否定式为 may not，缩写形式是 mayn't.

might 是may 的过去式，有两种用法，一种表示过去式，一种表示虚拟语气，使语气更加委婉，客气或对可能性的怀疑。

He told me he might be here on time.他说他能按时间来。

Might I borrow some money now.我可以借点钱吗?

He might be alive.他可能还活着。

must,need,ought to,dare (dared)用法

Must 必须，应该，一定，准是，表示说话人认为有必要做某事，命令，要求别人做某事以及对事物的推测。

must 用来指一般现在时和一般将来时，过去式可用 have to 的过去式代替。

I must finish my work today. 我今天必须完成我的工作。

You mustn't work all the time. 你不能老是工作。

Must I return the book tomorrow? 我必须明天还书吗?

After such a long walk,you must be tired. 走了这么长的路，你一定困了。

He must be the man I am looking for. 他一定是我要找的人。

He had to go because of somebody's calling him that day. 那天他要走是因为有人叫他。

must + have + 过去分词，表示现在对过去事物的推测。

He must have told my parents about it.他一定把这件事情告诉我父母亲了。

He must have received my letter now.他现在一定收到我的信了。

It's six o'clock already,we must have been late again.已经六点钟了，我们一定又迟到了。

must 和 have to 的区别:must 表示说话人的主观思想，have to 表示客观需要。

You must do it now.你必需现在就干。(说话人认为必须现在干)

I have to go now.我得走了。(客观条件必须现在走)

need 需要 多用在否定式或疑问句中.

Need I attend the meeting tomorrow?我需要明天参加会议吗?

You need not hand in the paper this week.这一周你不必交论文。

need 是一个情态动词，用法完全和其他情态动词一样，但 need 还可当作实义动词使用，这时 need 就象其他动词一样，有第三人称，单复数，后面加带 to 的动词等特性。

I need a bike to go to school.我上学需要一辆自行车。

Do you need a dictionary?你需要词典吗?

She needs a necklace.她需要一条项链。

needn't + have + 过去分词 表示过去做了没必要做的事情。

You needn't have taken it seriously.这件事情你不必太认真。

dare 敢, 多用在否定或疑问句中。

The little girl dare not speak in public.小女孩不敢在公众面前说话。

Dare you catch the little cat?你敢抓小猫吗?

dare 除用作情态动词外，更多的是当实义动词使用，用法同实义动词一样，要考虑人称，单复数，时态等。

Do you dare to walk in the dark?你敢黑夜走路吗?

He doesn't dare to tell the teacher what happened that day.他不敢告诉老师那天发生的事。

have to,ought ，will ，Shall,should . ought 应当，应该 后面跟带有 to 的动词不定式。

You ought to read these books if you want to know how to repair the motorcar.如果你想知道如何修理汽车，你应该读这些书。

You ought to bring the child here.你应该把孩子带来。

ought + to have done 句型。指过去动作，表示一件事情该做而未做。

You ought to have been here yesterday.你昨天就应该来。

ought not to have done 句型。表示一件不该做的事情却做了。

You ought not to have taken the book out of the reading-room.你不应该把书带出阅览室。

will (would)决心，愿望。would 为 will 的过去式，

可用于各人称。

I'll do my best to catch up with them.我要尽全力赶上他们。

I'll never do it again,that's the last time.我再不会做那件事情了，这是最后一次。

He said he would help me.他说他会帮助我。

will,would用于疑问句表示说话人向对方提出请求或询问，用 would 比 will 更婉转，客气。

It's hot. Will you open the windows?天气太热了，你能打开窗户吗?

Will you help me to work it out?你能帮我解这道题吗?

Would you like some coffee?给你来点咖啡怎样?

Shall,should表示命令，警告，允诺，征求，劝告，建议惊奇。

You should hand in the exercise book.你应该交作业本了。

This should be no problem.这应该没问题。

Shall we go now.我们现在可以走了吗?

Why should I meet him?为什么我要见他?

have to，不得不，必须，表示客观条件只能如此，而must 则表示主观思想必须。

I have to go now.我现在得走了。

I have to cook for my child.我得给孩子做饭。

You must be here on time next time.你下次一定要按时来。

We must go to get the timetable ourselves.我们一定要自己去拿时刻表。
 .
  编辑本段情态动词+havedone的用法.
 


must have done sth.一定做过某事

can/could have done sth.本来能够做某事，而实际上未做

can't/couldn't have done sth.不可能做过某事

ought to/should have done sth.过去本应该做某事而实际上并没有做
本段有关情态动词的练习题.