be的三种用法（be的三种基本用法）

1 forms

Be is the most common verb in English. It is used in many different ways.

The present tense forms of be are am, are, and is, and the past tense forms are was and were. Be is both an auxiliary and a main verb.

... a problem which is getting worse.
It was about four o'clock.

Am, is, and are are not usually pronounced in full. when you write down what someone says, you usually represent 'am' and 'is' using 'm and 's.

'I'm sorry, ' I said.
'But it's not possible,' Lili said.
'Okay,' he said. 'Your brother's going to take you to Grafton.'

You can also represent 'are' using 're, but only after a pronoun.

'We're winning,' he said.

You can also use the forms 'm, 's and 're when you are writing in a conversational style.

2 used as an auxiliary

Be is an auxiliary when forming continuous tenses and passives. 当形成连续时态和被动语态时，Be是助动语。

She was watching us.
Several apartment buildings were destroyed.

In conversation, get is often used to form passives.

3 used as a main verb

You use be as a main verb when you are describing things or people or giving information about them. After be, you use a complement. A complement is either an adjective or a noun group.

We were very happy.
He is now a teenager.

4 indicating someone's job

When be is followed by a noun group indicating a unique job or position within an organization, you do not have to put 'the' in front of the noun.

At one time you wanted to be President.

Note that make is sometimes used instead of 'be' to say how successful someone is in a particular job or role. For example, instead of saying 'He will be a good president', you can say 'He will make a good president'.

5 indicating age and cost

You can talk about a person's age by using be followed by a number.

Rose Gibson is twenty-seven.

You can also use be to say how much something costs.

How much is it?
It's five pounds.

6 with prepositional phrases

You can use many kinds of prepositional phrase after be.

He was still in a state of shock.
I'm from Dortmund originally.
... people who are under pressure.

7 with 'to' -infinitives

You sometimes use 'to'-infinitives clauses after be.

The talks are to begin tomorrow.
What is to be done?

8 in questions and negative clauses

When you use be as a main verb in questions and negative clauses, you do not use the auxiliary 'do'.

Are you O.K?
Is she Rick's sister?
I was not surprised.
It was not an easy task.

9 in continuous tenses

Be is not usually a main verb in continuous tenses. However, you can use it in continuous tenses to describe someone's behaviour at a particular time.

You're being very silly.

10 'be' and 'become'

Do not confuse be with become. Be is used to indicate that someone or something has a particular quality or nature, or is in a particular situation. Become is used to indicate that someone or something changes in some way.

Before he became Mayor he had been a tram driver.
It was not until 1845 that Texas became part of the U.S.A.

11 after 'there'

Be is often used after there to indicate the existence or occurrence of something.

Clearly there is a problem here.
There are very few cars on this street.
There was nothing new in the letter.

WARNING: You cannot use be without there to indicate that something exists or happens. You cannot say, for example, 'Another explanation is' or 'Another explanation must be'. You must say 'There is another explanation' or 'There must be another explanation'.

12 after 'it'

Be is often used after it to describe something such as an experience, or to comment on a situation.