PAST PERFECT SIMPLE AND P.P. CONTINUOUS

 1. had been visiting.
 2. had been looking.
 3. had left.
 4. had been raining/ ´d been.
 5. hadn´t seen.
 6. hadn´t drunk.
 7. had forgotten.
 8. had been working.
 9. hadn´t been waiting.
10. ´d suggested/ had been studying.