Do and does are used to form questions and negatives in the simple present tense. Does is used with singular nouns and third person singular pronouns (he, she, it). Do is used with plural nouns and plural pronouns (they, we and you). The pronoun I is an exception to this rule. Though it is a singular in number, it is used with do.

Do you play football? Yes I do.

Does he speak English? Yes, he does.

Do you know the answer? No, I don’t.

Does she love him? No, she doesn’t.

As you can see, do and does are also used in short answers.

Do you eat meat? Yes, I do. (NOT Yes, I eat.) (The answer ‘Yes, I eat meat’ is grammatically correct, but it doesn’t sound natural.)

Does she work here? No, she doesn’t. (More natural than ‘No, she doesn’t work here.’)

Do / does: emphatic use

As you can see, do and does are used to make questions and negatives. They are not normally used in affirmative sentences. However, we can use them for emotive emphasis when we feel strongly about something.

I do love him. (More emphatic than ‘I love him.’)

She does look beautiful in that gown. Quiet stunning! (More emphatic than ‘She looks beautiful in that gown.)

You do look nice today!

She thinks I don’t love her, but I do love her. I really do!

I don’t see my old friends often, but I do call them every now and then.

Were you joking? I do believe you were pulling my leg.

When we use do and does for emphasis, we give them extra stress in pronunciation.

Did is mainly used for making questions and negative sentences in the simple past tense. It is also used in short answers.

Did you see John? Yes, I did. (NOT Yes, I saw.)

Did you receive the letter? No, I didn’t. (NOT No, I didn’t receive.)

In affirmative sentences in the simple past tense, we can use did for emotive or contrastive emphasis.

I did lock the door. (More emphatic than ‘I locked the door’.)

She did come. (More emphatic than ‘She came.’)

Almost everybody was away on holiday, but I did manage to see Alice.

Forming questions using intonation

We sometimes form questions by using a rising intonation at the end of the sentence. In this case, we use the normal word order. Do and does are not used in these questions.

You are quitting? Why?

You want to marry him? I can’t believe this. He’s so boring!