D. must表示偏偏要做...,表示与说话人愿望相反及不耐烦,表示一种重要或急迫的事情.

1. Though she needn't, she must go. 偏偏

2. You didn't have to come again, but you must. 偏偏

3. We have to care for the the young. 义务.

4. ---How old are you, madam? ---If you must know, I'm twice my son's age.

E. must也可以作名词,表示必须做看或听等的事情.

His new novel is a must for all lovers of crime fiction.

4. 比较will和would

注意：

1)would like;would like to do = want to 想要，为固定搭配。例如：

Would you like to go with me? 想和我一块去吗?

2)Will you...?　Would you like...? 表示肯定含义的请求劝说时，疑问句中一般用some, 而不是any。例如：

Would you like some cake? 吃点蛋糕吧。

3)否定结构中用will，一般不用would, won't you是一种委婉语气。

Won't you sit down? 你不坐下吗?

4) 表示意志或意愿,will表示现在, would指过去

I will never do that again.

They said they would help us.

5) 表示请示或建议时,用would比用will委婉和客气.

Will/ Would you please pass him the book?

6) 表示习惯性动作,总是,惯于,will指现在,would指过去

Fish will die without water.

Every evening, she would sit by the window, deep in thought.

7) 表示预料或猜想,表示大概会......

It would be about 10 when he left home.

I thought he would have told you about it.

5. 比较used to和would的区别

1)表示过去重复的习惯时,两个都可以.

He would/used to take a walk near the forest in the evening.

2)used to强调过去的行为同现在的对比,含有过去怎样,现在却不这样了, would则单纯表示过去的习惯性动作,常与often, every day等连用

He used to be a very strong man.

She isn't what she used to be.

We would sit in the yard every evening and listen to his story.

我们每天晚上坐在院子里,听他讲故事.

3)表示过去的状态,只能用used to,不可用would

There used to be a temple on the top of the mountain.

6. 比较need和dare

这两词既可做实义动词用，又可做情态动词用。作为情态动词，两者都只能用于疑问句，否定句和条件句。need 作实义动词时后面的不定式必须带to，而dare作实义动词用时, 后面的to 时常可以被省略。

1) 实义动词：need(需要, 要求) need + n. / to do sth

We need to tell him the news.

You don't need to tell him the news.

Do the flowers need watering?

2) 情态动词：need，只用原形need后加do，否定形式为need not。例如：

Need you go yet? 你要走了吗?

Yes, I must. / No, I needn't.是的，我要走了/不，不急着走.

---Need I help you? ---Yes, please.

You needn't ask him the question.

dare表示"敢,敢于",作情态动词,主要用于疑问句,否定句和条件从句,一般不用于肯定句中.

---Dare you go alone there?

--- Yes, I dare./ No, I daren't.

How dare he do such a thing?

用作实义动词时,其变化形式和一般动词相同.在肯定句中,dare后通常接带to的不定式，在否定句和疑问句中，dare后面既可带to也可不带to.

Would you dare to catch the snake with your hand?

The boy dares to do anything he likes.

No one dares to swim in that river.

He doesn't dare (to) climb that tall tree.

Don't you dare (to) touch it?

How dare you (he)...?表示愤怒，谴责，不表示疑问

How dare you call him a liar?你怎敢说他撒谎?

I dare say/I daresay 我相信，可能

She will keep her word, I dare say. 我想她会守信用的。

---I would imagine he's forgotten. --- I dare say.

7. ought to/ should

A. ought to 应该

You ought to take care of him.

--- Ought I to go now?

--- Yes, you ought to./No, you oughtn't to.

表示推测，表示某个情况是合理的，符合逻辑的

He must be home by now. 断定

He ought to be home by now. 不十分肯定

B. ought to/ should

should表示自己的主观看法，而ought to语气重，含有按道理应该，如果要反映客观情况或涉及法律义务和规定时用ought to. ought to在省略答语中，如果表示本应该或本不应该时，要在to后加have,除此之外要加to.

1. You should help them with their work.

2. You are his father. You ought to get him to receive a good education.

should的用法

1.表示义务，"应该"，用于各种人称

You should be polite to your teacher.

You shouldn't spend so much time playing computer games.

2.表示推测，"想必，估计"的意思.

If they start today, they should arrive there in two days.

3.表示与想象的不一样"照说应该......"

I wonder where Mary is. she should be here now.

4.在某些从句中，表示虚拟语气.

He suggested that I (should) go to shanghai tomorrow.

He demanded that we (should) solve the problem at once.

5.表示惊讶，忧虑，惋惜等感情色彩.

I am surprised he should eat so little every day.

8.shall/should

shall表示应该,常指法律、条约或协定中的义务和规定。

You shall not do it like that. 可能是违法或违反协定

You should not do it like that. 仅是劝解

与第二或第三人称连用，用于陈述句中，表示说话人的意图、命令、允诺、警告

You shall have a lot of money. 意图=I'll give you a lot of money.

You shall get your photos before tomorrow noon.

He shall be punished if he still stays here.

与第一或第三人称连用，询问对方的意见或请求指示。

Shall we begin now?

Shall the driver wait outside or give him an hour's rest?

A: Shall he come in? B: Ok.

make offers

I'll wash your sports jacket.

Shall I get a ticket for you?

Shall we carry the books for you ?

should表示应该，常有一种道义上的责任或义务;居然，竟然，常表惊讶、忧虑、惋惜或高兴的情绪，Why/How should...?竟会，表示说话人对某事不能理解，感到意外和惊讶;表示推测时，表示确定的或可能有的未来或期望。

You should do it because you have promised to.

I can't believe such a gentleman should be so rude to the old.

I'm surprised he should eat so little every day.

Why should he think like that? I can't believe it.

It's nearly 7. Jack should be here at any moment.

9. will表示说话人的意愿或固执己见，用于非人称主语时，表固有性质或倾向。

I won't allow her to do that.

The window won't open.

The door won't shut.

情态动词的其他常见用法：

cannot...too/enough 无论怎样...也不过分，越...越好

You cannot be too careful.你越小心越好。

You can't remember enough English words.你记的英语单词越多越好。

cannot but do=have to

I could not but choose to go.

I cannot but admire your bravery.

may well do sth.完全能，很可能

Her appearance has changed so much that you may well not recognize

(4) may as well do sth= had better do最好，满可以，倒不如

You may as well do it at once.

情态动词+have done意义的正确理解

may/might+have done 用于推测过去的行为，"可能""也许/或许已经(没有...)

If we had taken the other road, we might have arrived earlier.

2.can/could have done 表示过去能做而未做的事情，有种惋惜。"本可以"

I had no class yesterday evening, you could have borrowed my book.

用于推测过去的行为，"可能，会..."

Where can/could she have gone?

The boy can't have finished reading the book so soon because it is very difficult.对过去发生的行为和不肯定，常用于否定句和疑问句中。

3.must have done---对过去的肯定推测

must do---对现在的肯定推测

must be doing---对未来或现在正进行的推测

must have done 的反意疑问句

You must have seen the film, haven't you?

You must have seen the film last week, didn't you?

His parents must have beaten him, haven't they?

His parents must have beaten him yesterday, didn't they?

needn't have done做了本来没必要做的事情

You needn't have watered the flowers for it is going to rain.

It is a five-minute walk from the station to my house. You needn't have taken a taxi.( However, you did take a taxi.)

should/ought to have done

You shouldn't have told David what Mike told you.(Actually. You did tell David what Mike said.)

Exercises:

1. He might/may have gone to Shanghai, but I'm not sure.

2. He must have gone to Shanghai, because he said if he wasn't at work,

that's where he would be.

3. He can't have gone to Shanghai. I saw him just now in the library.

宁愿做某事：

would rather do sth.

would rather do sth. than do sth.

would rather sb. did sth.

would do sth. rather than do sth.

prefer to do sth.

prefer to do sth. rather than do sth.

prefer doing to doing

高二英语必修4教案就为大家介绍到这里，希望对你有所帮助。

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