Negative sentences in English use an auxiliary verb plus not. The main verb shows tense and agreement, and not marks the sentence as negative. Some verbs do not need do as an auxiliary in the present simple and past simple.

Rule
A negative sentence uses an auxiliary verb and not to make the meaning negative.
The main verb carries tense and agreement, and not attaches to the auxiliary.
In present simple and past simple, do is the auxiliary for negatives unless the verb is be, have got, or a modal.

In the present simple, use do not or does not before the base verb. In the past simple, use did not before the base verb. The main verb stays in the base form after do not, does not, or did not.

Subject	Form
I, you, we, they	do not + base verb
he, she, it	does not + base verb
all subjects	did not + base verb

The verb be forms negatives by adding not directly after be. No extra auxiliary is needed, and be carries the tense and agreement. This pattern works for present and past forms of be.

Subject	Form
I	am not
he, she, it	is not
you, we, they	are not
I, he, she, it	was not
you, we, they	were not

Modal verbs form negatives by placing not after the modal. The modal shows tense or meaning, and the main verb stays in the base form. Do not is not used with modals.

Subject	Form
all subjects	can not + base verb
all subjects	will not + base verb
all subjects	should not + base verb
all subjects	must not + base verb

English often uses contractions for negatives by joining the auxiliary or modal with not. The contracted form replaces not and sounds more natural in speech. Some contractions have irregular spelling.

Word/Phrase	Definition
don't	The contraction of do not.
doesn't	The contraction of does not.
didn't	The contraction of did not.
isn't	The contraction of is not.
aren't	The contraction of are not.
wasn't	The contraction of was not.
weren't	The contraction of were not.
can't	The contraction of cannot.
won't	The contraction of will not.

Have forms negatives with do not or does not in most uses. British English often uses have got, which forms negatives with not after have. The choice depends on the structure, not just the meaning.

Rule
Have as a main verb usually takes do not or does not for negatives.
🇬🇧Have got forms negatives with have not got.
Have as a main verb keeps the base form after do not or does not.

Negative sentences often use not, but English also has negative words like never, nothing, nobody, and nowhere. These words usually appear without another not in the same clause. The verb still follows normal auxiliary rules.

Word/Phrase	Definition
never	A negative word meaning at no time.
nothing	A negative word meaning not anything.
nobody	A negative word meaning no person.
nowhere	A negative word meaning no place.

Not usually comes after the auxiliary, modal, or be, and before the main verb or complement. Negative words like nothing and nobody appear in the position of subjects or objects, not as a replacement for not. Double negatives are not standard in most varieties of standard English.

Rule
Not follows the auxiliary, modal, or be in the sentence.
Negative words do not combine with not in the same clause in standard English.
Subjects and objects with negative words use normal auxiliary patterns.

English negatives use an auxiliary plus not, with do for present and past simple, be with not, and modals with not. Contractions make negatives more natural in speech. Negative words like never and nothing create negative meaning without another not.