Временная форма The Past Perfect Continuous

had been + Ving
ОБРАЗУЕТСЯ ПРИ ПОМОЩИ: вспомогательного глагола had been
основного глагола с окончанием -ing

Передает длительное действие, которое началось до определенного момента в прошлом и продолжалось в этот момент.
I had been teaching at that school for some time before I met you.
Одно действие, продолжавшееся некоторое время в прошлом, повлияло на следующее действие или состояние:
He knew the city very well because he had been working as a taxi driver for ages.
действие

Эта временная форма выглядит одинаково для всех лиц и чисел:
I had been working.
We had been working.
You had been working.
He (she, it) had been working.
They had been working.

ВОПРОСИТЕЛЬНА ФОРМА
Had you been working?
Had she been working?

Отрицательная форма
I had not been working.
They had not been working.