pronoun+be not
I am not hungry.
I'm not hungry.
That dog is not friendly.
That dog isn't friendly.
She is not my sister.
She's not my sister.
She is not my sister.
She isn't my sister.
He is not my brother.
He's not my brother.
He is not my brother.
He isn't my brother.
They are not friends.
They're not friends.
They are not friends.
They aren't friends.
We are not late.
We're aren't late.
We are not late.
We're not late.