Réponse :
Bonjour,
1. The fire was extinguished by the firefighters
2. The boy was operated by the surgeon
3. The thief was arrested by the police
4. The malicious software was stolen from the NSA by hackers
5. the Twin Towers were destroyed by two planes
6. The theory was discovered by the scientist
Explications :
Dans une phrase au passif, le complément d'agent ( introduit par "by" ) est celui qui fait l'action.
ex. 2. Le garçon a été opéré par le chirurgien.