Perfect tense

Present Perfect Tense is used for describing a past action’s effect on the present: He has arrived. Now he is here. This holds true for events that have just been secluded as well as for events that have not yet occurred. Past Perfect Tense is a kind of tense that is used to describe an action or an event that started in a certain time in the past and completed or finished  till  certain time in the past too; or past perfect tense is used to express an action or an event that had happened before the other event or action happened

Present perfect is formed by combining have/has with the main verb’s past participle form:

I have arrived.

A negation is produced by inserting not after have/has:

I have not arrived.

Questions in present perfect are formulated by starting a sentence with have/has:

 Has she arrived?

The pattern :

 (+) Subject + had+verb III+cmplement

 (-) Subject + had not+ver III+complement

 (?) Had + subject +verb III+complement