by agent - Passive

Passive - Explanations: Summary; Active - Passive (Sample word); Active - Passive (Sample sentence); by-agent; Active sentence - Passive sentence (two objects); Verbs with prepositions in Passive; Personal Passive - Impersonal Passive

Passive sentences with by

We are normally not interested in the "doer" of an action in a passive sentence. When we want to mention the "doer", we use the preposition by. The whole phrase is called by-agent in English.

Active sentence	Passive sentence
Mr Brown built the house.	The house was built by Mr Brown.

When we do not know, who was the "doer" of the action, we use someone or somebody in the active sentence. We leave out these words in the passive sentence.

Active sentence	Passive sentence
Someone stole my bike.	My bike was stolen.