Positive
I | have | a dog. |
He/ She/ It | has | |
We/ You/ They |
have |
Negative
I | don't have (do not have) | a car. |
He/ She/ It | doesn't have (does not have) | |
We/ You/ They |
don't have (do not have) |
Question
Do | I have | the keys? |
Does | He/ She/ It have | |
Do | We/ You/ They have |
Negative and question forms need the auxiliary verb 'do'.
In this case the auxiliary verb 'do/does' doesn't have any meaning.