Por ejemplo:

1) to have (tener)

I have two cats.

Do you have two cats?

I don't have to cats.


When they were children they had a pink bicycle.

Did they have a pink bicycle when they were children?

When they were children they didn't have a pink bicycle.



2) to do (hacer)

What are you doing now?

I'm doing my homework now.

I'm not doing my homework now.


She has just done a cake.

Has she done a cake yet?

She hasn't done a cake yet.



3) to be (ser/estar/haber)

I was at school yesterday.

Where were you yesterday?

I wasn't at school yesterday.


Have you ever been in England?

We have never been in England.

We have been in England two times.