I Способ образования, вспомогательный глагол
had + been Ving HAD
+ I\you\he\she\it\we\they had been playing
- I\you\he\she\it\we\they hadn`t been playing
? Had I\you\he\she\it\we\they been playing
II. Случаи употребления
1.Действие, которое началось в прошлом и длилось определённый период времени до другого действия или момента в прошлом.
They had been looking for a house for six month before they found one they liked
2. Действие, которое длилось определённый период времени в прошлом и имело видимый результат в прошлом
Last Friday Ron had to fly to New York. His flight was delayed. He was annoyed. He had been waiting at the airport for 3 hours.
III Указатели
for, since, how long, before, until