"Studyis Past Perfect continuous tense"

It is used to express a continued or ongoing action that started in past and continued until sometime in past. (Remember, an ongoing action in past which continued till some time in past) There will be a time reference, such as “since 1980, for three hours etc” from which the action had started. A sense of time reference is found in these sentences which shows that action had started in past and continued till some time in past.  Such time reference or sense of reference is the identity of Present perfect continuous tense because it tells that action has started from a particular time in past or for some time period. For example, “He had been studying in this school since 2005”, so the it means that he had started his education in this school in 2005 and he studied in this school till sometime in past.

Note: If there is not time reference or sense of time reference, then it is not Past perfectcontinuous tense because there is no hint about the time of action when it started in past or continued for some time period, so it seems just an ongoing action in past which resembles “past Continuous tense”. So the reference of time differentiates between Past perfect continuous tense and past continuous tense.

Rules: An auxiliary verb “had been” is used in sentence. 1st form of verb (base verb) +ing (present participle) is used as main verb in sentence. “Since” or “for” is used before the “time reference” in sentence. If the time reference is exactly known such as 1995, 4 O’clock then “since” is used before the time in sentence. If the time reference is not exactly known such as three hours, six years, four days, then “for” is used before the time in sentence. Time reference such as 3 hours or 5 days is not exactly known because we don’t know that about which three hours a day is told in sentence or about which 5 days in a month is told in sentence. While the 1995 is exactly known time.

                                   Structure of sentence.

Positive Sentence.
• Subject + Auxiliary verb + main verb (Present participle) + Object + Time reference
• Subject + had been + (1st form of verb or base verb + ing) + object + time    reference

Examples.
      I had been waiting for him for one hour.
      She had been playing chess since 7 O’clock.

Negative Sentence.
• Subject +”Not” between the Auxiliary verbs + main verb (present participle) +     Object + Time reference
• Subject + had not been + (1st form of verb or base verb + ing) + object + time    reference

To make negative sentence, the word “not” is added inside auxiliary verb, so it becomes “had not been”.
Examples.
        I had not been waiting for him for one hour.
        She had not been playing chess since 7 O’clock.

Interrogative Sentence.
• Auxiliary verb+ Subject + Auxiliary verb + main verb (present participle) + object +    time reference
• Had + Subject +  been + (1st form of verb or base verb+ing) + object + time    reference

Interrogative sentence starts with auxiliary verb “had” and auxiliary verb “been” is used after subject in sentence.
Examples.
        Had I been waiting for him for one hour?
        Had she been playing chess 7 O’clock?

More examples.

Positive sentences
         I had been living in America since 2003.
         He had been playing cricket for two hours.
         They had been watching television since 6 O’clock.
         She had been working in this office since 2007.
         It had been raining for three days.

Negative sentences
        I had not been living in America since 2003.
        He had not been playing cricket for two hours.
        They had not been watching television since 6 O’clock.
        She had not been working in this office since 2007.
        It had not been raining for three days.

Positive sentences
        Had I been living in America since 2003?
        Had he been playing cricket for two hours.
        Had they been watching television since 6 O’clock?
        Had she been working in this office since 2007?
        Had it been raining for three days?