Question

Chang to passive voice : my grand father built this house in 1943
2: Picasso was painting Guernica at that time
3: the cleaner has cleaned the office
4:he had written three books before 1862

Answer 1

This house was built by my grandfather in 1943

Guernica was painted by Picasso at that time

The office has been cleaned by the cleaner

Three books were written by him before 1862

Answer 2

1 This house was built by my grandfather in 1943