1) table capacity

Can stands for ability, which means that you can do something with little resistance by physical strength, brain power or technology.

I can climb this pole.

He is only four years old, but he can read. He is only four years old, but he can read.

Fire cannot destroy gold. Fire cannot destroy gold.

Because can can't be used with other auxiliary verbs, we use will can to represent the future tense.

You can skate after two or three times of practice.

You can skate after practicing for two or three times.

2) Form possibility

It is often used in negative sentences and interrogative sentences, but it can also be used in affirmative sentences.

Can the news be true? Can the news be true?

This is not true. This can't be true.

What could he possibly mean? What could he possibly mean?

Can is used in affirmative sentences to express theoretical possibility (temporary possibility).

A horse in central London may be worth a lot of money.

Going to the dance can be very exciting.

The road can be blocked. This road may be blocked.

May's possibility of expressing reality with affirmative sentences.

This road may be blocked. This road may be blocked.

3) Allow (similar to may) is common in spoken English.

May I come in? may I come in?

Can I smoke here? May I smoke here?

2.2. the usage of could

1) indicates the possibility and permission in the past, (mostly used as indirect speech)

At that time, we thought that the story could not be true.

At that time, we thought that what we said could not be true.

Father said I could swim in the river.

Dad said I could swim in the river.

2) Table past ability

I could swim when I was six years old.

I could swim when I was six years old.

When Could expresses past abilities in affirmative sentences, it often expresses abstract general abilities.

He may have been naughty when he was a child.

He would be very naughty when he was a child.

3) Table "Allow". Ask questions or state opinions politely.

May I use your bike?

Yes, you can.

Will he remember?

I'm afraid I can't give you an answer today.

I'm afraid I can't answer you today.

The teacher said that you can go to the store to buy candy.

The teacher said that you can go to the store to buy sugar.

3) The structure of could/can+haddone indicates "doubt" or "uncertainty" about what happened in the past. Could plus perfect is also used in affirmative sentences, generally indicating actions that may have been completed in the past but have not yet been completed.

Could they have won the basketball game?

Did they win the basketball game?

What you just mentioned may make her very sad.

What you just said may make him very sad.

You could have finished the task earlier.

You could have finished the task earlier. (But in fact, the task was not completed ahead of schedule.)

I could have passed the exam easily, but I made too many stupid mistakes.

I could have passed the exam easily, but I made too many mistakes that I shouldn't have made.

If you specify your ability to do something, you must use "can".

He can translate this article without a dictionary.

He can translate that article without a dictionary.

Energy refers to consistent ability, and energy refers to objective ability and ability that can be achieved through hard work.

I can't swim. But I am sure that with more practice, I will be able to swim.

The fire spread throughout the hotel, but everyone was able to escape.

When the ship sinks, he can swim to the shore.

3.3. the usage of may

1) means request, permission, permission.

You can drive a tractor. You can drive that tractor.

2) When answering the question caused by may, the negative answer should be "no", which means "no", "no" and "no".

may I come in?

Yes, you can.

No, you can't.

No, you can't.

No, you can't.

No, you'd better not

3) The conjectural usage of May/MightMay

He may be right.

He may not come today.

He may come tomorrow.

Note: 1 is only used for affirmative and negative sentences, not for interrogative sentences.

2 may be less than possible.

He may find a job.

He may find a job.

3 it may be impossible, impossible, impossible.

He may not come.

He can't come.

3) Form suggestion (can also be used with)

You might as well stay where you are.

You'd better stay where you are (Might as well mean "it is better to ...")

4) Express wishes

May you be happy!

probably

1) The past "possible" and "allowed" were mostly used in indirect speech.

She said that he might take her dictionary.

She said that he could use her dictionary.

Except in indirect speech, the past might generally does not mean "possible" and "allowed". The past "possibility" of the table can be could, and the past "permission" of the table can be were (was) allowed.

2) Possibility is less than possibility.

Electric irons may be dangerous; They may surprise you.

Electric irons can be dangerous. It may electrocute people.

3)may +have +done means speculation about past behavior, and means "probably" and "possibly".

This may be true. It may be true.

He may not have solved the problem yet. He may not have solved the problem yet.

4.4. The main usage of must

1) means necessary.

We must do everything step by step. We must do everything step by step.

Why do you always bother me? Why do you have to bother me?

2) The structure of the predicative "must be+"usually means guessing and "certain". (Used in affirmative sentences only)

He must be an honest boy. He must be an honest boy.

This must be your room. This must be your room.

3) There are two negative expressions of MUST: when answering the questions caused by MUST, the negative answer should be needn't or unnecessary, which means "unnecessary", "unnecessary" and "not necessarily". Must not is used when it means "should not", "not allowed" or "prohibited".

Must I go tomorrow? Must I go tomorrow?

Yes, please. Yes, please!

No, you don't have to go.

4) The structure of "must+have+past participle" is often used in affirmative sentences, indicating speculation about past behavior, and indicating "must" and "must be". Can is used in negative sentences and interrogative sentences.

She must have studied English before. She must have studied English before.

The meaning of have to is very close to that of must, but have to emphasizes objective needs and must emphasizes subjective views.

I must clean the room. (subjective idea)

I must clean the room. (objective need)

In addition, have to can be used in more tenses:

We must get there at ten o'clock. We must be there at ten o'clock.

We will have to reconsider the whole thing.

We will have to reconsider all this.

You don't have to do it.

6. usage of 6.oughtto

Ought is followed by the verb prototype, which means obligation, but not as confident as must, for example:

You don't look well. You should see a doctor.

You don't look well. You should see a doctor.

Oughto is used in negative sentences, and its negative form can be abbreviated as oughtn, such as:

You shouldn't smoke so much. You shouldn't smoke so much.

Can also be used in interrogative sentences, such as:

Should you smoke so much? Should you smoke so much?

We should use indirect speech to express the past tense, such as:

He said you should tell the police.

He said you should report it to the police.

7.7. usage of shall

1) is used to solicit the opinions of the other party in the first person, such as:

What should I wear on the trip? What should I wear on the road?

Shall we dance? Shall we dance?

2) The second and third person schedules used by 2)shall for promises, warnings, orders and threats (now rare), such as:

She will get her share. She can get her share.

You'll get it back tomorrow. You can get it back tomorrow.

Generally speaking, the modal verb should should not be regarded as the past tense of the modal verb shall. The main uses are:

1) is used to ask the other person's wishes in first-person interrogative sentences, but the tone is euphemistic and gentle, such as:

What should we do now? What should we do now?

2) it means that it should, must and often be used interchangeably with must. For example:

We should master at least one foreign language.

We should master at least one foreign language.

3) The structure of "should+be+predicative" indicates speculation or surprise. For example:

They should be back by now. They should be back by now.

I'm sorry that she was so careless. I regret that she should be so careless.

4) the structure of "should+have+past participle" means 4) "should+have+actions or behaviors that have been done in the past but have not actually been done; Its negation refers to something that should not have happened. Its synonymous structure "should have+past participle" means "should have" and "should have" in the past, with strong tone. For example:

I should have thought of that. I should have thought of that. (But I didn't expect it)

They should not leave so soon. They shouldn't leave so early. (But he has already left)

5) In the sentence pattern of "very natural (strange, natural, necessary, surprising, impossible, important)", the predicate verbs in the subject clause should be used to express "taken for granted", "strange", "necessary" and "amazing". Should+ verb prototype should also be used after lest, for fear (that), in case, etc. In clauses such as advise, sugar, order, demand, request, etc. , should+do "as an example:

It is necessary to send him there at once.

It is necessary to send him there at once.

It is strange that he should say so.

Let's go at once lest we miss the train.

Let's go at once lest we miss the train.

8 .. the usage of will and would

1) indicates will, determination or desire. For example:

We will definitely support all the people in the world in their struggle for peace.

We must support the people all over the world in their struggle for peace.

He wouldn't let me try. He wouldn't let me try.

2)will means regular, habitual and tendentious, and will means habitual behavior in the past.

He would sit there hour after hour, watching the passing cars.

He often sits for hours at a time, watching the passing cars.

He will come to see me when he is in Beijing.

He often came to see me when he was in Beijing.

3) When used in interrogative sentences with the second person as the subject, the tone of will is more than that of will.

Can you tell me the way to the station? Can you tell me how to get to the railway station?

4) Form possibility

This will be the book you are looking for.

This may be the book you are looking for.

She was about 60 when she died.

He was about 60 when he died.

9. Usage of needs and challenges

Modal verbs need notional verbs.

Now you need (not) to do what you (not) need to do.

exist

When he needs (does not need) to do it, he needs (does not need) to do it.

What does You Guo need (don't need) to do

Go ...

When he needs (doesn't need) to do something.

You need (not) to do what you will (not) need to do.

come

When he needs (not) to do it, he will (not) need to do it.

Sentence tense verb

Modal verbs dare, substantive verbs dare.

Dare to use the present tense/dare to do less.

I dare not do what I dared not do in the past.

Negative sentences in the present tense dare not/dare not do/dare not do.

I dare not do it without doing it in the past tense.

Does he dare to do it? What do you/he like to do?

In the past tense, did he dare? Does he dare to do it?

Needly have v-ed means to have done something in the past, but there is no need to do it, which means "there is no need ...". For example:

You needn't have woken me up; I don't have to go to work today.

10. Questions expressing conjectural modal verbs

He must/may be in the room, isn't he?

He can't be in the room, can he?

He must have finished the work, hasn't he?

He may have done the work last night, didn't he?

Modal Verb+Action Verb Progressive Aspect

Modal verb+action verb progressive aspect (that is, modal verb +be+v-ing) means to speculate or comment on whether an action is going on now. For example:

He must play basketball in his room.

She may stay at home.

1 1. Modal verbs+action verbs complete the progressive aspect.

Modal verb+action verb complete progressive aspect (that is, modal verb+always +v-ing) means speculating or commenting whether an action is going on or has been going on in the past. For example:

They should have held a meeting to discuss the problem.

He may be buying stamps at the post office when you see him.

12. Used for+v.

(1) is used as +v to indicate "frequently used" and "always used"; Be used to +v-ing/n (noun) means "used to"; Being used to +v means "being used to (do something)".

(2) Used to represent only the past, and used to +v-ing/n can represent the present, the past or the future. For example:

He used to smoke. Now he's gone.

He is used to hard work.

This knife is used to cut bread.

13. Other phrases used as modal verbs

I'd rather, sooner, (just) earlier, sooner, but I can't, but (just) can also be used as a modal verb. For example:

The soldier would rather die than surrender.

The brave soldier would rather die than give in to such an enemy.

I'd rather walk than take a bus.

If you don't like swimming, you might as well stay at home.

Note: These phrases usually follow the verb prototype directly. Would (had) rather, Would(had)only, Would(just)as only, clauses that can be guided by that are often omitted, and clauses should be in subjunctive mood. The assumption about present and future is past tense, and the assumption about the past is past perfect tense. For example:

I'd rather you came on Sunday.

I'd rather you didn't ask me to speak yesterday.