Past Perfect Passive

Passive Use:

The same as mentioned before with the other passive verb forms, we use the passive form when the focus is on the object of the phrase and not the subject. It is often used in journalistic English, when we do not know who caused the action or it isn’t important. Transforming this verb into the passive voice, is relatively easy. So in the passive form we add an extra particle to obtain this form. Therefore we transform as follows:
Active: bad driving had caused many accidents.
Passive: many accidents had been caused by bad driving.
According to the tense we are using we change the auxiliary of the verb to be and in this case we add Had because it is a past perfect tense. Ex: Accidents had + been caused by bad driving. Past Perfect.

Form

Auxiliary of the verb have had + been + past participle.

Affirmative form

Active form	Passive form
I had cleaned the house every day.	The house had been cleaned by me every day.
Triumph had made motorcycles.	Motorcycles had been made by Triumph.

Negative form

Active form	Passive form
I hadn’t cleaned the house every day.	The house hadn’t been cleaned by me every day.
Triumph hadn’t made motorcycles.	Motorcycles hadn’t been made by Triumph.

Interrogative form

Active form	Passive form
Had you cleaned the house every day?	Had the house been cleaned by you every day?
Had Triumph made motorcycles?	Had motorcycles been made by Triumph?

Note important! We can only form a passive sentence from an active sentence when there is an object in the active sentence.