Assim como do / does no presente, o passado tem o seu auxiliar: did — um só, para todas as pessoas.

	Presente	Passado
pergunta	Do you like it?	Did you like it?
negativa	She doesn't eat meat.	She didn't eat meat.
resposta curta	Yes, I do.	Yes, I did. / No, I didn't.

A regra de ouro: o passado já está no did, então o verbo volta à forma base:

• Did you go? — nunca Did you went?
• I didn't buy it. — nunca I didn't bought it.

Didn't é a contração de did not.