PAST PERFECT

 The past perfect is an English verb tense that is used when we talk about the past and we want to refer to something that happened before a specific point in the past.

A clear example. Look at the following two sentences, you will be able to see that they are finished actions in the past and that is why they are in the simple past.

John left yesterday morning at 8 am. (Juan left yesterday at 8 in the morning). Kevin went to visit John at 8:20 am. (Kevin went to visit John at 8:20)

past perfect affirmative 

In the affirmative, the past perfect is helped by had and the past participle of the verb that gives meaning to the sentence. The contraction ‘d is often used. Use the following structure: 

              Subject + had + past participle

past perfect negative 

The past perfect negative is helped by the auxiliary verb have in the past simple and the past participle of the verb accompanied by a 'not' in between. The contraction ‘hadn’t’ is often used. Use the following structure:

        Subject + had + not + past participle

past perfect interrogative 

The structure of the interrogative form of the English past perfect is: 

           Had + subject + past participle