The verb do - auxiliary and main verb

The verb do can be an auxiliary verb or a main verb in English.

do as a main verb in the Simple Present (do, does, don't, doesn't)

affirmative	negative
I, we, you, they:
I do my homework in the evenings.	I don't do my homework in the evenings.*
he, she, it:
He does his homework in the evenings.	He doesn't do his homework in the evenings.*

*Note: Here we use do in the negative sentence as an auxiliary and as a main verb.

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do as a main verb in the Simple Past (did, didn't)

affirmative	negative
I did my homework in the evenings.	I didn't do my homework in the evenings.**

**Note: Here we use did in the negative sentence as an auxiliary and do as a main verb.

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do as a main verb - past participle (done)

affirmative	negative
I have done my homework.	I haven't done my homework.

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do as a main verb (Present Progressive, Gerund, present participle) - (doing)

affirmative	negative
I am doing my homework.	I am not doing my homework.
Doing my homework is not always fun.	Not doing my homework is not clever.
I saw Jane doing her homework.	I didn't see Jane doing her homework.

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do as an auxiliary verb in negative sentences in the Simple Present:

I don't do my homework in the evenings.

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do as an auxiliary verb in negative sentences in the Simple Past:

I didn't do my homework yesterday evening.

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do as an auxiliary verb in questions in the Simple Present:

Do you like rugby? - Does he like rugby?

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do as an auxiliary verb in questions in the Simple Past:

Did you see Peggy yesterday?
When did you get up this morning?

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do with negative imperatives:

Don't sing under the shower.