Actions in progress before another past event: had been + verb-ing
Subject + had been + verb-ing
Subject + had not (hadn't) been + verb-ing
Had + subject + been + verb-ing?
💡 Often used with for/since to show duration, or with when/before to show sequence.
✓I had been studying for hours before the exam.
✗I had studied for hours before the exam (if emphasizing duration).
Continuous emphasizes the ongoing nature.
✓She was exhausted because she had been running.
✗She was exhausted because she had run.
Continuous shows the activity causing the result.
✓How long had you been waiting?
✗How long had you waited?
Continuous for duration questions.