高中英语情态动词详解及练习

高中英语情态动词详解

1. 表示请求和允许: can，could ，may，might. 过去式使语气更委婉，答语应用原形。

--- Could I use your computer tomorrow morning?

--- Yes，you can.( 否定回答可用：No，I’m afraid not.)

1)can表示理论上的可能性，指某事或情况可能发生，但并不说明实际上真的发生.

Children can be very tiring.

2)对现在事情的推测：情态动词+do

对过去事情的推测：情态动词+have done

对已完成事情的推测：情态动词+have done

3)反意问句：

He may know the plan，doesn’t he?

You must have studied English before，haven’t you?

You can’ t have been caught in the rain last night，were you?

3．can & be able to

在肯定句中can表示有“能力”做，be able to表示通过想办法/努力等而能够做成了某一件事，相当于managed to do…或succeeded in doing sth.

Birds can fly.

The fire spread through the hotel very quickly but everyone was able to get out.

4. may / might as well do sth“还是…好”、“不妨”

You might as well tell me the truth. 你还是把真相告诉我的好。

5. must和have to

1) must表示的是说话人的主观看法，而have to强调客观需要。

2）否定形式含义不同。mustn’t禁止，不许可，don’t have to不必

3) must 偏要（做令人不快的事）eg. Must you shout so loudly?

6. shall和should

1)表示说话人征求对方意见和向对方请示，用于第一、三人称。

When shall my father be able to leave hospital?

Shall2) 用于第一、三人称2) 用于第二、三人称，表示说话人给对方的命令、警告、允诺或威胁以及说话人的决心。

You shall go with me (命令)/ You shall have the book when I finish it.33（允诺）

He shall be punished （威胁）/ Nothing shall stop me from doing it. (决心)

3) 规定（在条约、规则、法律）

1)表示劝告和建议“应该”

2) “按道理应当”“估计”(=ought to)

They should be there by now，I think.

3）用于第一人称表示说话人的一种谦逊、客气、委婉的语气。

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

4）在条件句中表示“万一”，主句不一定用虚拟语气。

Ask Tom to ring me up if you should see him. /Should I be free tomorrow，I’ll come.

5）（Why / 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“竟然”，也用在某些从句中。

It seems so unfair that this should happen to me.这种事竟然发生在我身上真不公平。

7. will 和would

1)表示意志和意愿。will 指现在，would指过去。

If you will listen to me，I’ll give you some advice.

2)表示请求、建议，would比will委婉、客气。Will (Would ) you please pass me the book?

3)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.

4). 表示功能，意为“能” 或“行”The machine won’t work.

5) 表示预料或猜想。It would be about ten when he left home.猜想他离开家时大约十点。

8. would & used to

1)表示过去持续的状态和情况用used to；would不与表示状态的动词连用。

There used to be a hospital here. / There would be a hospital here.( ×)

2)would 常与often，sometimes，for hours等表示时间的副词（短语）连用。

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

3)used to 强调过去的行为同现在的对比，含有“过去怎样，而现在却不这样了”的含义. eg.He will not spend the money on books as he used to.

9. dare 和need

两者作为情态动词都不用于肯定句，常用于否定句、疑问句和条件从句中。习惯用语I dare say（可能，或许，我揣测）除外。实义动词用法同于一般动词。但在否定句中，dare 后的to可省略，即：don’t / doesn’t dare(to ) do…. need 作为实义动词时，用在否定句中时，其后的to不能省略。

He dare go there alone. ( ×)He dares to go there.

He dares not go there alone. ( ×)He dare not go there alone . / He doesn’t dare( to ) go there alone.

He stood there without daring lift his head.(×)He stood there without daring to lift his head. 10．情态动词+ have done，表示过去比较：情态动词+ do ，表示现在或将来。needn’t have done & didn’t need to do…