Respuesta:
Es sencillo. Cuando es he, she o it se usa "does".
Ejem:
- Does your brother play the trumpet?
No, he doesn't.
- Does Susan know the answer?
Yes, she does.
Por otro lado, cuando es we, they, you, I se usa "do".
Ejem:
- Do you understand the exercise?
No, I don't.
- Do they watch TV in the evenings?
Yes, they do.
Espero haberte ayudado!
