Past passive

Usamos la voz pasiva en pasado cuando nos interesa más el resultado de la acción que quien la lleva a cabo.
Puede estar en forma afirmativa, negativa o interrogativa.

Afirmativa	Negativa	Interrogativa
This cake was made by my mother	This cake wasn't made by my mother	Was this cake made by my mother?
Piercings were invented by the inuits	Piercings weren't invented by the inuits	Were piercings invented by the inuits?

Su estructura es la siguiente: Sujeto + pasado del verbo to be + verbo principal en participio 

Ejemplo:

The draw was borrowed by the pintor.
El dibujo fue borrado por el pintor.