The verb DO plays an enormous role in the English language. It is the most important verb after BE. The primary function of DO is as an auxiliary verb. In this role it is used to form questions and negative statements.
The verb DO can also be used as a main verb, as explained in this lesson.
Like all English verbs, except BE and modal verbs, the verb DO has two conjugations in the simple present: do | does.
singular plural
first person I do we do
second person you do you do
third person he, she, it does they do
Note that the third person singular form of the verb has -es added. All the other conjugations are do.
In fact, use of the verb DO as a main verb in the simple present is very limited. Its only purpose is to indicate who or what performs a habitual action or task. For example:
He does his homework at night.
We do it all the time.
The car does this when it is cold.
Machines do the difficult work.
Occasionally the verb DO is used as an auxiliary verb in affirmative statements in order to make a contradiction. For example:
assertion contradiction
Tom drinks tea. He doesn’t drink coffee. Yes, Tom does drink coffee.
I’m sorry, I don’t have a pen. Oh, I do have a pen! Here.
Susan doesn’t smoke. You’re wrong. Susan does smoke.
In the above examples, DO is stressed.
The verb DO has a single conjugation for all persons in the simple past: did.
singular plural
1st per I did we did
2nd per you did you did
3rd per he, she, it did they did
