Level B1
Perfect Passive
Perfect Passive: has been or have been plus the third form, when what has happened to the thing matters more than who did it. The letters have been sent. The house has been painted. Don't forget been.
The letters have been sent.
Look: The letters have been sent. We don't say who sent them.
Forms
The letters have been sent.— many things: have been + third formThe house has been painted.— a thing: has been + third formThe new school has been built.— irregular action words have their own third form
A common mistake
Wrong: The letters have sent.
Right: The letters have been sent.
A common mistake is to forget been. We say: The letters have been sent.
More examples
Dinner has been made.
Make becomes made: Dinner has been made.
Many books have been written about it.
Write becomes written: Many books have been written about it.