Past Perfect Continuous
action continuing a period up to a spe¬cific time in the
She had been working as a clerk for 10 years before she resigned.
past action of certain duration which had visible results in the past.
They were wet because they had been wolking in the rain.
the Past Perfect Cont. is the past equivalent of the Present Perfect Continuous
(She is going to the doctor. Her leg has bem aching for two days.) She went to the doctor. Her leg had been aching for two days.