Negative form of the Present Tense

Simple Present forms

Negatives in the simple present are formed by adding don't or doesn't before the simple form of the verb:

Subject	Auxiliary	Example
I	don't	I don't sing
You	don't	You don't sing
He	doesn't	He doesn't sing
She	doesn't	She doesn't sing
It	doesn't	It doesn't sing
We	don't	We don't sing
They	don't	They don't sing

In other words, only third person singular subjects (he, she and it) have doesn't — the rest have don't.

Para reforzar el tema, haz click en el siguiente enlace y practica lo aprendido.
http://www.agendaweb.org/exercises/verbs/present-negative