Auxiliary Verbs : To have

The conjugation of to have is as follows:

Negative sentences are formed by adding not, and questions by using inversion (read about inversion).

Questions and negatives in the Present Simple and Past Simple are formed using do, does and did, for example:

• Did you go to school today?
• She doesn't know my name.

In British English to express possesion have got is also used.

• Have you got a new car?

The verb to have is the most common auxiliary used for perfect tenses.

Important: have + to-infinitive is used to express duty and obligation.

• We have to tidy our rooms once a week.
• She had to see a doctor after 2 weeks.

Read about other uses of to have