They clean the room every day
The room is cleaned every day.
They have completed the work
The work has been completed.
You must finish the work.
The work must be finished.
People say he is famous
He is said to be famous.
Passive sentences sometimes include the doer using this word.
by
She writes emails
Emails are written.
They had repaired the car
The car had been repaired.
They can solve the problem.
The problem can be solved.
People believe she is honest.
She is belived to be honest.
The book was written ___ J.K. Rowling
by
They built a bridge.
A bridge was built.
They are painting the house.
The house is being painted.
They should have informed us.
We should have been informed.
People think they have left.
They are thought to have left.
When is by + agent" usually NOT used?
when the doer is unknown or unimportant
They are watching a movie
A movie is being watched
They were building a road.
A road was being built.
They might repair the car.
The car might be repaired.
People know he was a doctor
He is know to have been a doctor.
The window was broken." (No agent) — Why?
the doer is unknown / not important?
They will finish the project.
The project will be finished.
This tense: "The documents will have been signed."
Future Perfect Passive
They could have done it.
It could have been done.
This structure is called: "He is said to...
Impersonal Passive
"The cake was made by my mother." → Identify the agent.
my mum