The formula for the past perfect tense is had + [past participle]. It doesn't matter if the subject is singular or plural; the formula doesn't change.

What is the past perfect tense of past?

To form the past perfect tense you use the past tense of the verb "to have," which is had, and add it to the past participle of the main verb. For example: subject + had + past participle = past perfect tense.

Which tense is used for past?

The simple past tense shows that you are talking about something that has already happened. Unlike the past continuous tense, which is used to talk about past events that happened over a period of time, the simple past tense emphasizes that the action is finished.