tutoria-Nachhilfe-Wiki

Study this example:

This house was built in 1930. ‘Was built’ is passive. Compare active and passive:
o Somebody built this house in 1930. (active)
o This house was built in 1930. (passive)

We use an active verb to say what the subject does:
o My grandfather was a builder. He built this house in 1930.
o It’s a big company. It employs two hundred people.

We use a passive verb to say what happens to the subject:
o This house is quite old. It was built in 1930.
o Two hundred people are employed by the company.

When we use the passive, who or what causes the action is often unknown or unimportant:
o A lot of money was stolen in the robbery. (somebody stole it but we don’t know who)
o Is this room cleaned every day? (does somebody clean it? – it’s not important who)

If we want to say who does or what causes the action, we use by…:
o This house was built by my grandfather .
o Two hundred people are employed by the company.

The passive is: be (is/was/have been etc.) + the past participle (done/cleaned/seen etc.)