Do

The verb do is used as an auxiliary verb.

I do not want it.	We do not want it.
You do not want it.	You do not want it.
He does not want it.	They do not want it.

I did not want it.	We did not want it.
You did not want it.	You did not want it.
She did not want it.	They did not want it.

It can also be used as a main verb. See Types of main verb. When do is used as an auxiliary verb it is a supporting verb. Because a main verb cannot combine directly with negatives or make questions, do is used to support the main verb.

Don’t talk!
Don’t run!

It is also used to stand in for another verb to avoid repetition, as shown on Auxiliary verbs.The verb do is irregular. It has five different forms: do, does, doing, did, done. The base form of the verb is do. The past simple form, did, is the same throughout. The present participle is doing. The past participle is done.The present simple tense do and the past simple tense did can be used as an auxiliary verb. As an auxiliary, do is not used with modal verbs.

I do not want it.	We do not want it.
You do not want it.	You do not want it.
He does not want it.	They do not want it.

I did not want it.	We did not want it.
You did not want it.	You did not want it.
She did not want it.	They did not want it.

As an auxiliary verb do is used in the following ways:

to help make the negative and question forms of present simple and past simple tenses.

Oh dear, I didn’t feed the cat this morning.
Do you know what time it is?
Did Tim pay for his ticket last night?

to make the negative form of a command.

Don’t talk!
Don’t run!

to make a command more persuasive. See The imperative.

Do let me see it!

to avoid repeating a main verb in additions, commands, sentence tags, and short answers.

They often go to the cinema, and so do we.

Don’t run on the road! Don’t do it!

You live in Glasgow, don’t you?

Do you play cricket? – No, I don’t.
Did they tell you the news? – Yes, they did.
Jim likes jazz, I think. Yes, he does.

in comparisons.

She sings better than I do.

The positive forms of do cannot be contracted. In speech, the negative has contracted forms.

I don’t (do not) agree with you.
She doesn’t (does not) live here now.
They didn’t (did not) buy any food.

present tense negative forms:
I/we/you/they don’t; he/she/it doesn’t
past tense negative form:
I/we/you/he/she/it/they didn’t

When do is a main verb, it has a range of meanings that includes carry out, perform, fix, or provide. It is sometimes used in place of a more specific verb.

I’ll do the lawn now.
(I’ll mow the lawn now.)
I’ll do you.
(I’ll punch you.)
We don’t do coach parties.
(We don’t serve coach parties.)

It is then used with the full range of tenses and forms. See also The present simple tense.

Are you doing your homework?
You have been doing well this term.
She had done enough, so she stopped.
This has been done before.

The main verb use of do can be used to talk about:

habits.

I do the washing up every evening.
This what I usually do.

behaviour.

He did something rather foolish.
I didn’t do anything wrong.
What are you doing?

plans.

What are you doing on Sunday?

As a main verb, do makes negatives and questions like all other main verbs:

in the present simple tense with auxiliary do.

What does he do for a living?
Do I do it this way?
No, you don’t do it like that at all.

in the past simple tense with auxiliary did.

Did Henry do it, then?
Didn’t Henry do it, then?
He didn’t do it, you know.

This means that it is possible to use do twice in negative and interrogative sentences; once as an auxiliary verb and once as a main verb.

As a main verb, do can be used with modal verbs.

They will do it for you, if you ask nicely.
I can do it, but I shouldn’t do it.