Объясните мне пожалуйста в английском языке время Past Perfect Continuous! Заблаговременно

Время Past Perfect Continuous показывает на деянье, которое началось в прошедшем, длилось в течение некого времени и либо завершилось конкретно перед некоторым моментом в прошедшем либо все еще не закончилось к некоему моменту в прошедшем.

I had been typing this text for 2 hours and then found it on the Internet.
Я набирал этот текст два часа, а позже отыскал его в Вебе.

I had been waiting for his airplane for 2 hours when it was announced about delay.
Я ожидал его самолет теснее два часа, когда объявили об его задержке.
Образование Past Perfect Continuous

Утвердительные предложения:

I had been playing We had been playing
You had been playing You had been playing
He / she / it had been playing They had been playing
Вопросительные предложения:

Had I been playing? Had we been playing?
Had you been playing? Had you been playing?
Had he / she / been playing? Had they been playing?
Отрицательные предложения:

I had not been playing We had not been playing
You had not been playing You had not been playing
He / she / it had not been playing They had not been playing
Для того, чтоб поставить глагол в форму времени Past Perfect Continuous, нужно вспомогательный глагол to be во медли Past Perfect и причастие настоящего медли (форма V-ing) смыслового глагола.