| 
 
Structure: 
   
    | 
Affirmative:   | 
Subject +had +present
    participle form of verbs+ object/extensions |  
    | 
Negative: | 
Subject +had+
    not+ present participle form of verbs+ object/extensions |  
    | 
Interrogative: | 
Had +Subject +
    present participle form of verbs+ object/extensions? |  
    | 
Negative Interrogative: | 
Hadn’t +Subject
    + present participle form of verbs+ object/extensions? |  
 
Use
  of Past Perfect Tense:1: A completed action before something else in the past. 
 
2: To explain or give a reason for something in the past.When
       we arrived when the film had
       started. (= first the film started, then later we
       arrived) 
 
3: Stative verbs only: something that started in the past and
  continued up to another action in the past.I'd eaten dinner so I
       wasn't hungry.It had rained in the night,
       so the train didn't arrive in time. 
 
4: As part of the third conditional.When
       he graduated, he had
       been in Dhaka for six years. 
 (= he arrived in Dhaka six years before he graduated and lived there
       continuously until he graduated, or even longer)
 
 
If I had known
  you were ill, I would have visited you | 
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