Past perfect

Past perfect
The Past perfect is used for an action that was completed at some point in the past before something else happened.
It is formed using the past tense of the verb “have” and the past participle of a verb
In the negative form, use the past tense of the verb “have” + not + the past participle of a verb
In the interrogative form, use the past tense of the verb “have” + subject + the past participle of a verb