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