上海高中英语语法整理集-市重点内部资料

情态动词

情态动词是一种本身有一定的词义，但要与动词原形及其被动语态一起使用，给谓语动词增添情态色彩，表示说话人对有关行为或事物的态度和看法，认为其可能、应该或必要等。情态动词没有人和数的变化，后面加动词原形，没有不定式，分词或动名词的形式。

英语中主要的情态动词有：can, may, must, shall, will, dare, need等。

情态动词的用法和要点：

can 和could的用法

can 和could都表示能力或客观可能性，还可表示请求或允许。

Can you work out this math problem on your own? （能力）

Water can be changed into ice.（客观可能性）

Can I go now? (Could I go now? 这里could 用在疑问句中，表示语气委婉，并不表示过去式，回答应用Yes, you can.) (表示请求)

can表示能力时，可以用be able to代替，但当我们要表示“某事已成功”时，应用 was(were) able to (相当于manage to do 或succeed in doing) 而不能用could。此外，be able to 可以用于各种时态。

He can/is able to enter for the English contest. .(能力)

They will be able to tell you the news soon.（将来时态）

He was able to flee Europe before the war broke out.

=He managed to flee Europe before the war broke out.

情态动词can, could用在否定、疑问句中表示推测，怀疑或惊讶。

He couldn’t be a wealthy man.(推测)

You can’t be hungry so soon, Tom. You have just had lunch.（怀疑）

How can that be! （惊讶）

may和might的用法

may 和might都表示允许或请求。在语气上 might比 may委婉。此时 may的否定式是mustn’t，表示“不可以，禁止”。can 也可以表示允许，多用于口语，语气比较随便。在句型May/Might…?中，表示征求对方许可，在文体上比较正式，在语气上较为客气。在日常生活中常用Can I…?征求对方意见更为常见。

You may (can) ring us up any time during office hours.

Can/ May (Might) I have your name?—Of course, you may/can.

May I take the magazine out of the reading-room?—No, you mustn’t.

Could I leave for a while?

表示可能、推测（一般不用于疑问句中）。此时may的否定式是may not（可

能不），can’t表示不可能。might表示推测时，如指现在的情况，只是表示可能性比may 小，并不表示过去。may放在句首，表示祝愿。

Don’t disturb him. He may (might) get angry.

She may not go to the concert tonight.

Our teacher said that he might test us on grammar the next day.

May God bless you!

must 和have to 的用法

两词都是“必须”的意思，must表示说话人主观上的看法，have to表示客观

的需要。must的否定式，不能用mustn’t，而要用needn’t或don’t have to，表示“不必”。mustn’t (禁止，不许)是may的否定式。

My brother was very ill, so I had to call the doctor in the middle of the night.（客观上需要做这件事）

He said that they must work hard.（主观上要做这件事）

Must we hand in our exercise books today?

—Yes, you must. (No, you needn’t ./ No, you don’t have to.)

You mustn’t waste our time.

must只有一种形式——现在式，而have to有人称、数、时态的变化，但must

可用于间接引语中表示过去的必要或义务。

Everyone must obey the traffic rules when driving in the city.

They have to empty the house because a couple will soon move in.

I am afraid you will have to wait a while.

He told us we must all be ready by nine.

must表示推测。must用在肯定句中表示较有把握的推测，比may肯定得多，意为“一定”或“准是”。must表示对现在的状态或现在正发生的事情的推测时，后面通常用动词的进行式。否定式则用can’t来表示。

You have worked hard all day. You must be tired.

Grandpa Liu must be over eighty years old.

You ate a big cake half an hour ago. You can’t be hungry now.

He must be working in his office.

She can’t be waiting for us at the bus stop because I saw her in the room just now.

will和would的用法

用于各种人称，表示“意志”、“意愿”和“决心”。

Who will take the difficult job? I will.(愿意)

They would walk home though it was raining heavily.（意志）

I have advised her not to give up the plan, but she will.（决心）

用于第二人称疑问句中，Will you…?或Would you like…?句型中，表示征求

对方意见或请求、建议。would较will语气婉转。

Will you be so kind as to open the door for me?

Would you like to have a drink with me? —Yes, of course.

Would you mind showing me the way to the hospital?

表示一种习惯性动作或状态，will表示“总是”，would表示“过去总是”。

Water will boil at 100 degree Centigrade.

We would play jokes on each other when we were in the countryside.

He would come to see us during his stay in Beijing.