English Tense: Past Perfect Continuous
(Subject + had + been + Present Participle...)
The Past Perfect Continuous Tense expresses an action that had been going an for some time in the past. In order to use this tense we use had been with Present Participle (ing) form of the verb.
Examples: Children had been playing since morning. It had not been drizzling since last night. (Negative)
Had you been waiting for me for two hours ? (Interrogative)
(b) The Past Perfect Continuous Tense is also used to express an action that had seen going on for some time before another action took place in the past:
They had been playing chess for two hours when I joined them.
The Chinese had been preparing for war for many years before they attacked
We had been standing in a queue for half an hour before the bus arrived.
(i) In Interrogative form, ‘had’ precedes the subject and ‘been’ comes after the subject:
Had he been quarrelling with you for some time?
Hadn’t they been preparing hard for the examination ?
(ii) In negative form, ‘not’ is placed after ‘had’ and before ‘been’:
They had not been working on this project for many years.
He had not been thinking to go abroad.