Question

Como cambio a voz pasiva: Many people visit the park.
The maid washes the windows.
I write beautiful poems.
He studies Biology.
The teachers congratulate the studens.
You found that old book yesterday.
Peter sold his car.
They prepared a delicious cake.
The fire destroyed those houses.
Paul painted the classrooms.

Answer 1

The windows are washed(by the maid)
Poems are written (by me)
Biology are studied(by him)
The students were congratulated(by the teachers)
That old book was found yesterday(by you)
The car was sold(by him)
A delicious cake was prepared(by they)
Those houses were destroyed(by the fire)
The classrooms were painted(by paul)

Lo que esta en parentesis es opcional...puede ser agregado a la oracion

Espero haberte ayudado :)