Данная вид о-в реме иная форма употребляется:

1. для выражения действия, которое закончилось до определенного момента в прошлом. Этот момент может быть обозначен обстоятельством прошедшего времени или другим действием в прошлом.

Matilda had finished reading the book by 9 o'clock (by that time, by Saturday).

Yuri had done the work by the time his parents returned. They had finished the project by the end of the year.

2. с глаголами, не имеющими формы продолженного времени, для выражения действия, которое началось до определенного момента в прошлом и все еще было в процессе в этот момент.

Не told me he had been badly ill since he returned from the South.

I knew that they hadn't seen each other for many years.

He realized he had been in love with her for a long time.

They had owned the house for twenty years when they decided to sell

it.

3. для выражения двух прошедших действий, одно из которых находится в процессе, а второе завершилось к началу первого действия.

The sky had cleared and the moon was shining on the snow. Rita had done the work and was speaking on the telephone.

4. в сложноподчиненных предложениях с придаточными времени, вводимыми союзами: scarcely ... when, hardly ... when, no sooner ... than («не успел ... как», «едва ... как»).

Обратите внимание на порядок слов: глагол had предшествует подлежащему для создания стилистического эффекта. Hardly had the children got out of the house, when they saw a stranger in the yard.

No sooner had Mary entered the garden, than she saw a beautiful bird.

Scarcely had the spy left the pub, when the policemen caught him.

PAST PERFECT CONTINUOUS

(ПРОШЕДШЕЕ ЗАВЕРШЁННОЕ ДЛИТЕЛЬНОЕ)

Утвердительная форма
I			I had been walking for
We			2 hours
You	had been V-ing		She had been walking
They She			for 2 hours
He
Отрицательная форма
I			I had not been walking
We	had not	been	for 2 hours
You	(hadn't)	V-ing	She had not been
They			walking for 2 hours
She
He

Вопросительные конструкции:
Общий вопрос	Альтернативный вопрос	Разделительный вопрос	Специальный вопрос
Had they been talking for 2 hours?	Had they been talking for 2 or 3 hours?	They had been talking for 2 hours, hadn't they?	How long had they been talking?

Указатели времени:

for two hours, for a month, for the last two days (weeks, years), since 5 о 'clock.