The past perfect continuous tense is used to describe an action that started in the past, continued for some time, and ended before another past event. It’s formed using had been + verb + -ing.

It’s used to:

Show the duration of an action before another event: "She had been studying for hours before the test."

Describe cause and effect: "He was tired because he had been running all morning."


For questions, place "had" before the subject: "Had you been waiting long before the bus arrived?" For negatives, use "had not" or "hadn't": "They hadn't been living there for long when they moved."