Isn't, haven't, don't, etc.

This lesson explains negative forms and common contractions in English. You will learn how to form negatives with auxiliary verbs (do, be, have, modals), where contractions go, and when to use full forms instead of contractions in formal contexts.

• Negatives use auxiliary verbs: do/does/did, be (is/are/was), have (has/have), and modals (can, will).
• Contractions combine the auxiliary + not (don't, doesn't, isn't, haven't).
• Use do-support (do/does/did) for present simple and past simple negatives when there is no other auxiliary.
• In formal writing avoid contractions; in spoken/business emails contractions are common.

The negative word 'not' attaches to the auxiliary verb. If there is no auxiliary, use do-support.

• With be: subject + be + not — She isn't available.
• With have (perfect): subject + have + not + past participle — They haven't finished.
• Present simple: use do/does + not + base verb — He doesn't attend the meeting.
• Past simple: use did + not + base verb — We didn't receive the invoice.

Contractions like don't, isn't, haven't are common in speech and informal writing; avoid them in formal documents.

Learners often make predictable errors with negatives and contractions. Watch out for these universal pitfalls:

• Using 'don't' with third-person singular subjects (write 'doesn't' instead).
• Mixing up 'haven't' and 'hasn't' for third-person singular.
• Forgetting do-support: saying 'She not like it' instead of 'She doesn't like it'.
• Using double negatives unintentionally (e.g., 'I don't need no help').
• Overusing contractions in formal writing where full forms are more appropriate.

Check subject-verb agreement and whether an auxiliary is required.