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 of finished certain time in the past too ; or past perfect tense is used to express an action or an event that had happened before that other event or action happened.

Formula of Verbal sentence          :

(+)     Subject + had + V3

(- )      Subject + had + not + V3

(?)     Had + Subject + V3

 E.g : (+)   She had put my book on the table last night

          (-)   She had not put my book on the table last night

        (?)   Had she put my book on the table last night ?

Formula of Nominal Sentence

(+)     S + Had + Been + Non Verb

(- )      S + Had + Not + Been + Non Verb

(?)     Had + S + Been + Non Verb ?

E.g :  (+) I had been there when the accident happened

       (-) I had not been there when the accident happened

       (?) Had been there when the accident happened ?