2018年专四英语情态动词语法考点

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　　考试中，情态动词部分重点测试以下内容：

(1)情态动词+行为动词完成式

(2)某些情态动词的特殊用法

1. must have v-ed

must have v-ed 表示推测过去某事“一定”发生了。其否定形式为：can’t / couldn’t have v-ed, 表示过去不可能发生某事。

例如：

Since the ditch is full of water, it must have rained last night.

2. could have v-ed 表示推测过去某动作“很可能”发生了

3. may / might have v-ed 表示推测过去某事“也许”发生了 比 might 表示的可能性在说话人看来稍大些。

t to / should have v-ed 和 ought not to / shouldn’t have v-ed 用于对已发生的情况表示“责备”、“不满”，分别表示“本应该…”和“本不应该…”表示应完成而未完成的动作用于完成时中的否定句，表示不应完成但已做的动作

n’t have v-ed 表示过去做了某事，但没有做的必要，意为“本没必要…”。

例如：You needn’t have waken me up; I don’t have to go to work today.

注意：did not need to do 动作并没发生

例：I didn’t need to get up early,so I got up until 9 a.m.

　　*特殊用法

(1) can‘t表示“不可能”， may not 表示“不可以”， mustn’t(must not) 表示“不许可 禁止”，needn't (need not) 表示“不必”，dare not +动词原形 表示“不敢”

(2) must表推测 的否定现在式用can’t ,过去式用couldn’t

(3)May I / we …?这一类疑问句的肯定回答为Yes, please.或Certainly;否定回答为Please don’t.或No, you mustn’t. 例如：

“May we leave now?” “No, you mustn’t. You haven’t finished your home work yet.”

(4) need I / we …?这一类疑问句的肯定回答为Yes, we must; 否定回答为needn’t

(5)在回答must引起的问题时，如果是否定的答复，不能用mustn’t，而要用needn’t或don’t have to

(6)May/might as well may……but….(表转折)

(7) I wish to go home with you, may I?

(8) Do help yourself to have fruit, won’t you/ will you? (表示一种委婉的请求)

　　*情态动词短语的使用

would like to do…

would rather do…

would rather + 从句

would prefer to do...

had better do...

*情态动词: will(愿意), shall(将), must(必须), can, may, would, should(应该), might, could, ought to, used to(过去常常), need(需要), dare(竟敢)，have to(不得不)

*dare, need 也可作一般(行为)动词

*情态动词一般用法的否定：

mustn’t 不准, 禁止，不要 can’t(couldn’t) 不会;不能;

may (might) not 不可以;

needn’t 没必要 ( = don’t have to )

used not/usedn’t to或didn’t use to… 过去不…

dare not 不敢

*情态动词推测用法

Must 一定，肯定 can’t (couldn’t) 不可能

Can/ could 可能 Can’t (couldn’t) 不可能

may/ might “可能，也许” May (might) not 也许不，可能不

*推断用法

should/ought to“按理应当，应该是; shouldn’t 不应该 ( = ought not to )

*情态动词+have +done结构表示对过去动作的`推测

1. must have done：对过去的肯定推测，译作“一定做了…”，只能用于肯定句中。

其否定形式为can’t/couldn’t have done?

It must have rained last night, for the road was quite muddy

2. can/ could have done：对过去的可能性推测，译作“可能做了…”。只能用疑问句中

Can/Could he have said it? 他可能说过那种话吗?

3. may / might have v-ed：对过去的可能性推测，译作“也许能，有可能。

It’s too late. I think he may have gone to bed.

*情态动词+have+过去分词结构表示轻微的责备和后悔

肯定：过去应该做而没有做;

否定：过去不该(不必)做而做了。

⑴ might/could+have+过去分词：“本来可以，早就应该”

(只用于肯定句，且不能用may, can)

You could have told me you were going to be late!.你应当早告诉我你会晚到的!

⑵ should(ought to)+have+过去分词：“本应”(没做)

should not(ought not to)+have+过去分词：“本不该”(做了)

You should not have handed in your composition yesterday morning.你本不应把作文交了。

You should have been here earlier.你应该早点来才对。

3. needn't+have+过去分词：“本不必，本不须”(need只用于否定句)(做了)

You needn't have woken her up. It's only six.你其实不必叫醒她。现在才六点。

注意：did not need to do 动作并没发生(没做)

例：I didn’t need to get up early, so I got up until 9 a.m.

　　*八大注意点

1.在以could, might 表示征询对方意见或表示请求时，回答应相应使用can, may

— Might I watch TV after supper? — Yes, you ________.

A. may B. must C. might D. can

2. May I / we …?这一类疑问句的肯定回答为Yes, please.或Certainly;否定回答为Please don’t.或No, you mustn’t. 例如：

“May we leave now?” “No, you mustn’t. You haven’t finished your home work yet.”

3. need I / we …?这一类疑问句的肯定回答为Yes, we must; 否定回答为needn’t

4. 在回答must引起的问题时，肯定must; 如果是否定的答复，不能用mustn’t，而要用needn’t或don’t have to

5. I wish to go home with you, may I?

6. Do help yourself to have fruit, won’t you/ will you? (表示一种委婉的请求)

l 用于第三人称，表示许可，允许

8. let’s do this job, shall we? Let us do this job, will you?

9. should 也表示惊讶的语气，

例如：I was shocked that she should have said such a thing to you.(她竟然对你说那样的话,…)

*四大特殊结构

might as well + 动词原形”意为“最好，满可以，倒不如”，相当于had better

You may as well do it at once.

well + 动词原形”是一种常见的结构，意为“(完全)能，很可能”

He may well be proud of his son.

他大可为儿子高兴。

3. cannot … too / enough 表示 “无论怎么……也不算过分”、“越……越好”

You cannot be too careful.

4. had better 最好

You had better not wake me up when you come in.

　　*两大类区别：

　　一、表示能力: can, be able to

be able to 能用于各种时态。

can / could 只能表示现在或过去的能力

*was / were able to : “设法做成某事”

相当于 managed to do sth succeeded in doing sth.

　　二、used to 和would 的区别

used to过去常常(但现在已无此习惯，would无此含义)

He used to drink beer, now he drinks wine.他过去喝啤酒，现在喝白酒。

would只能用来谈动作;used to用来谈动作或状态(可与be, live, like, stay等状态动词连用)：

He would get up early when he lived in the country.他住在乡下时总是早起。

We used to live in a small town.(不能用would)

Be used to doing sth: 习惯于做某事