Answer:
Any action or an event that started in the recent past and express idea of completion or occurence, in relation to another event, without an exact time of its completion is in the past perfect tense.
Past perfect is also used for actions completed in the recent past, not a very long time ago.
The past perfect tense form of a verb has two parts:
The past tense form of ‘to be’ – known as helpingverb or auxillary verb
Past participle form of the main verb.
The structure of the sentence:
Affirmative sentences:-
Subject + helping verb + main verb + object
subject+ had + main verb (in past participle form) + object
Example: Farah had completed her homework.
In case of two events one happening after the other:
Subject + helping verb + (event 1) main verb (past participle form) + link + object + (event 2) main verb (in simple past form)
Example: The sun had set before the party started.
Note that here two events are described
Event 1: The sun set (in past perfect tense)
Event 2: The party began (in simple past tense)
Linking these events: before
Interrogative sentences:-
Helping verb + subject + main verb + object
Have/has + subject + participle form of main verb + object
Example: Had Farah completed her homework?
Negative sentences:-
Subject + helping verb + NOT – main verb + object
Subject + had NOT + participle form of main verb = object
Example: Farah had not completed her homework.