How to Use Didn't or Doesn't (Explained, Examples & Quiz)

What's the past tense of "do"?

The simple past tense of do is did, and the past participle is done. The negative forms are didn't (did not) for past tense and doesn't (does not) for present tense.

Definition of do

The Oxford English Dictionary defines do as "to perform, execute, or carry out an action; to accomplish or complete something; to act or behave in a specified way." It's one of the most common verbs in English and functions both as a main verb and as an auxiliary verb.

The past tense of do is did.

The past participle of do is done.

Verb forms of 'do'

Simple Cont. Perfect Perfect Cont.

Present

I/you/they do • He/she/it does

Past

I/you/they did • He/she/it did

Future

I/you/they will do • He/she/it will do

Present

I am/you are doing • He/she/it is doing

Past

I was/you were doing • He/she/it was doing

Future

I/you will be doing • He/she/it will be doing

Present

I/you have done • He/she/it has done

Past

I/you had done • He/she/it had done

Future

I/you will have done • He/she/it will have done

Present

I have been doing • He/she/it has been doing

Past

I had been doing • He/she/it had been doing

Future

I will have been doing • He/she/it will have been doing

Is "do" a regular or irregular verb?

Answer: Do is an irregular verb— its past conjugations are did and done.

Note: Regular verbs end in -ed in the past tense. Any other verb ending is considered irregular.

While an irregular verb, 'do' shows a highly common verb-conjugation pattern. Similar to other verbs like have/had/had, go/went/gone, and make/made/made, do uses different forms for past tense and past participle.

Similar irregular verbs

Past: did

Past part: done

When to use "didn't" (past) vs. "doesn't" (present)

He didn't do his homework yesterday.

He doesn't do his homework when I ask him.

The verb participle form of a verb (shown in the second sentence) uses the auxiliary verb have as a contraction, I've.

When auxiliaries like have or had appear in the same sentence as a past participle verb form, this indicates that the verb's aspect is in the present or past perfect, and not the simple past tense.

Remember, a participle always uses a helper verb to form the complete tense or aspect. Simple tenses, on the other hand, can stand on their own.

Sentence examples: do, did, done

Do (present tense)

• I do my homework every day.

• She does her best in everything.

• They do their chores on weekends.

Did (past simple)

• I did my homework yesterday.

• She did her best on the test.

• They did their chores last weekend.

Done (present or past perfect)

• I have done my homework already.

• She has done her best work.

• They had done their chores before dinner.

Synonyms & nearby words

Synonyms for do

perform execute accomplish complete carry out achieve fulfill conduct undertake manage

Nearby phrases

do up do over do away with do without do in do out do well do badly

FAQs

What's the past tense of "do"?

The past tense of "do" is "did."

What's the past participle of "do"?

The past participle of "do" is "done."

Is "do" a regular or irregular verb?

"Do" is an irregular verb; its past forms are not made by adding -ed.

When do you use "didn't" vs "doesn't"?

Use "didn't" for past negative actions for all subjects, like "I didn't go." Use "doesn't" for present negative actions for third-person singular subjects (he, she, it), like "He doesn't like it."

How is "do" used as an auxiliary verb?

"Do" is used as an auxiliary verb to form questions, negatives, and emphasis. Examples: "Do you like it?" "I don't like it." "I do like it."

Sources

Oxford English Dictionary. "do, v." OED Online. Oxford University Press. Date of access 15 Oct. 2025.
Cambridge Dictionary. "do." Cambridge University Press. Date of access 15 Oct. 2025.