（8）shall的用法

主要用于第一人称的疑问句中，表示征求对方意见。如：

What shall I do now?我现在该干点什么

Shall we go together?咱们一起走好吗

(9) should的用法

①表示“劝告、建议”，译作“应当”

You should study hard.你应当努力学习

You should listen to the doctor’s advice.你应当听大夫的话

We should help each other.我们应当互相帮助

②表示“推测、可能”

They should get home by now.他们现在该到家了

The book should be available in the bookstore.这本书在书店里可能有卖的

③后接动词不定式的完成式时，表示过去的事情，肯定结构表示该做没做；否定结构表示不该做，但发生了。

I should have written you earlier.我应当早引起给你写回信（但没写）

You shouldn’t have told him this.你不应当把这告诉他。（但告诉了）

(10) will, would的用法

主要用于第二人称的疑问句中，表示说话人向对方提出请求，would较 will更客气些

Will you help me? 你能帮帮我吗？

Would you like some tea? 你想喝点茶吗？

Will you please tell me the way to the station? 请问到车站怎么走？

(11) used to的用法

后接动词原形，表示以前经常发生的动作，但现在不是这样了（通常用于肯定句中）。

I used to get up early，我以前经常早起（现在不是这样了）

He used to read aloud everyday. 他以前天天朗读（但现在不是了）

注意：句型“be + used to”后接动名词或名词，表示“习惯……“：

I am not quite used to the weather, here. 我不大习惯这里的天气

Are you used to the food in Beijing?你现在习惯吃北京的饭了吗？

I’m used to getting up early.我习惯早起。

II. 情态动词must, may, might, could, can表示推测：

以must为例。must + do(be)是推测现在存在的一般状态进行；must + be doing 推测可能正在进行的事情；must +have done是推测可能已经发生过的事情。

1. must“肯定，一定”语气强，只用于肯定句中。

He must be a man from America. / He must be talking with his friend. / He must have already arrived there.

2. may和might“也许”，后者语气弱，更没有把握。可用于肯定句和否定句。

He may not be at home. / They might have finished their task.

3. can和could“可能”，could表示可疑的可能性，不及can’t语气强，用于肯定、否定、疑问句中。

The weather in that city could be cold now.

We could have walked there; it was so near.（推测某事本来可能发生，但实际上没有发生）

Can he be in the office now? No, he can’t be there, for I saw him in the library just now.(语气很强，常用于疑问句和否定句中)

【注意】：1.对现在的事实进行推测：

主要结构：…must / may / might +动词原形

be+名词/形容词/介词短语

be + doing

例句：

1. You must be Jeanne. I’m Mathilde Loisel. We used to know each other very well.

2. They must be in bed already at this time of the night.

3. The teacher must be joking.

4. Freda isn’t in class. She must be sick.

5. There must be something wrong.

6. She might be very clever, but she hasn’t got much common sense.

7. He may be arriving this evening.

8. He may be traveling around the world.

9. The keys can’t be in the room. I have just searched it very carefully.

10. Can the news be true ?

2．对过去的事实进行推测：结构：情态动词+have done / been+名词/形容词/介词短语。例句：

1. Mrs. Longmans must have been a pretty girl in her youth.

2. He couldn’t have seen Anna yesterday. She’s gone abroad.

3. I think I must have left my glasses in the library.

4. He might have overslept again.

5. Where can Tom have gone ?

Ⅲ.情态动词表达虚拟语气：表达“本来…”，“不然早就…”。这是情态动词的一种虚拟语气用法。表示说话人所讲的与所发生的事实相反。表达了说话人的埋怨，后悔的语气。其结构是在一些情态动词后面加 have done 结构。根据要表达的意思，有如下结构：

(1).should have done / ought to have done：本应该……

(2).shouldn’t have done / oughtn’t to have done：本不该……

(3).could have done：本来可以……

(4).needn’t have done：本来没必要……

(5).would like to have done：本来很想……

(6).would rather not have done: 本来不愿意……

(7).could / might / have done: 不然早就……

〈例句〉：1. You shouldn’t have laughed at his mistakes.

2. You could have told us earlier.

3. You ought not to have spent so much time in reading novels.

4. We need not have been in a tearing hurry to catch the train.

5. They would like to have seen that film last film.

6. If he had given me his number, I could have telephoned him.

7. They might have been frozen to death but for the rescue in time.

Ⅳ. 情态动词注意点：

1. can和be able to: 都可以表示能力。但be able to可以表达“某事终于成功”，而can无法表达此意。Be able to有更多的时态。另外，两者不能重叠使用。

2. used to和would: used to表示过去常常做现在已经不再有的习惯，而would只表示过去的习惯或喜好，不涉及现在。

3. need和dare作情态动词和实义动词的区别：

两者作情态动词时常用于否定句和疑问句。其形式为：needn’t/daren’t do；Need/dare…do…?

做实义动词时可用于肯定句，否定句和疑问句。其形式为：need(needs/needed)/dare(dares/dared) to do, don’t(doesn’t/didn’t) need/dare to do

注意：句型I dare say+从句。 意思是：我肯定…… = I’m sure或There is no doubt that+从句。例句：

I dare say that my uncle will get the money if I die.