NegationsRemember AGAIN:
The verb 'to be' is a special one. So are 'can' and 'have got'.
If its the first verb in the sentence: just add not.
She sings very beautiful. She doesn't sing very beautiful.
They can swim very well. They can't swim very well.
They cannot swim very well.
He has got a dog. He hasn't got a dog.
But...
He has a dog. He doesn't have a dog.