The structure of Past Perfect Passive is: Subject + had + been + past participle of the verb
In the Past Perfect Passive, the subject of the sentence is the recipient of the action that was completed before another action or time in the past. This structure is used when you want to emphasize the result of an action that was finished at a specific time in the past, and it had an effect on the subject. The focus is on what was done to the subject, rather than who performed the action.
We use the auxiliary verb "had" followed by "been" and the past participle of the main verb. This form shows that the action was completed before another event or time in the past.
Active: They had repaired the car before we arrived.
Passive: The car had been repaired before we arrived.
Active: The company had launched a new product by the time I joined.
Passive: A new product had been launched by the company by the time I joined.
Active: They had completed the research project before the deadline.
Passive: The research project had been completed before the deadline.
Active: People had forgotten about the event before the announcement was made.
Passive: The event had been forgotten before the announcement was made.
Active: The researchers had discovered a new species before they published the paper.
Passive: A new species had been discovered by the researchers before they published the paper.
Active: The government had approved the new law, and it was implemented the following year.
Passive: The new law had been approved by the government, and it was implemented the following year.
Active: The team had completed the design, and it had been reviewed by the client.
Passive: The design had been completed by the team, and it had been reviewed by the client.