Bonjour,
Réponse :
1. He found the child in the park.
The child was found in the park.
2. They broke the glasses with a stone.
The glasses were broken ( by them ) with a stone.
3. She saw the mouse in the kitchen.
The mouse was seen ( by her ) in the kitchen
.4. I polished the furniture in the afternoon
The furniture was polished ( by me ) in the afternoon.
5. He made the dress.
The dress was made by him.
6. Somebody pushed Mary into the water
.Mary was pushed into the water ( by somebody )
7. People from all over the world visited the museum.
The museum was visited by people from all over the world.
Explications :
Passif : be au temps de la phrase active + participe passé
Toutes les phrases sont au prétérit ( simple past )
→ was/were + participe passé
Le complément d'agent introduit par "by" est souvent sous -entendu