高三英语 虚拟语气

情态动词

I can , could (could 是can的过去式)

1）表示“能力”，“许可”，“可能性”，“惊异”。

He can sing. （能力）

He could sing when he was young.（能力）

You can go now. (许可)

At that time, I didn’t think the story could be true. (可能性)

What on earth can this mean? (惊异)

2) could 可以代替can，表示语气较为婉转

Could you wait for me at the school gate?

3) can和be able to 都表示能力，be able to 形式较多，并且表示成功地做某事。He was able to flee Europe before the war broke out.

= He managed to flee Europe before the war broke out

= He succeeded in fleeing ----

We shall be able to finish the work next week.

4) 表示推测：否推：can’t be --, can’t have done--; 疑问推测：Can he be---?

You look quite young. You can’t be forty. ( are you?)

The light is still on. They can’t have gone to bed. (have they?)

Can you be forty?

What can they be talking about? （会在讨论什么呢？）

Can he have written the book alone? （这本书会是他独自写的吗？）

5) 虚拟could have done （本可以，原可以做）

You could have come.

6) 用在目的状语从句中

He got up early in order that/ so that he could / might catch the early bus.

II. may , might

1)表示允许或征询对方许可，有“可以”意思，否定形式为may not (可以不)，但在表示

“不可以”，“禁止”，“阻止”时，用must not.

You may go now.

May I watch TV after supper?

Yes, you may. No, you mustn’t. 或No, you may not. No, you’d better not.

在请求对方许可时，可用Might I---? 表示更礼貌。

2）表示可能性，有“或许”，“可能”意思。

可能性推测：may /might do---/ may/might have done---

He may be right.

He may/ might come today.

He may/ might have missed the train.

III. must, have to, ought to , should

1)must 表示“必须”，“应该”，否定式must not, 不应该，不准，禁止。

Everybody must obey the rules.

You mustn’t speak like that to your mother.

Must I be home after 8 o’clock?

Yes, you must. No, you needn’t.

2)must 表示肯定推测（一定，必定，准是）must be/ must have done

You must be hungry after the long walk, aren’t you ?

He must have gone to Beijing, hasn’t he?

He must have gone to the cinema last night, didn’t he?

3) must 常有“偏偏” 的意思

Why must you interrupt me now and then when I was talking?

我在讲话时你为什么偏偏要不时地打断我?

The telephone must ring when I was busy in the kitchen.

我在厨房忙, 偏偏电话铃响了.

4) must侧重说话人的主观色彩,而have to侧重表示客观情况限制不得不做的事We must empty the room so that we can get it painted soon.

我们必须把房间搬空, 这样我们就能马上油漆.

We have to empty the room because a couple will move in soon.

我们得把房间搬空, 因为有一对夫妇户马上要搬进来.

don’t have to do ---没有必要做--- You don’t have to worry about that.

5) ought (not) to do --- 应该做---= should (not) do—

You ought to/ should follow your father’s advice.

should/ought to have done 该做而没做(含有责备之义)

shouldn’t /oughtn’t to have done 不该做却做了(含有责备之义)

He ought not to have kept us waiting so long.

6) should 表示“万一”