Answer: B) Had arrived.
Explanation for this question is being written.
Answer: B) Had left.
Answer: A) Had been stolen.
Answer: D) Had started.
Answer: B) Had painted.
Answer: D) Primary and middle school last studied online last week.
Answer: B) Past perfect.
Answer: A) Had passed.
Answer: C) Had started.
Answer: B) Had finished.
Answer: A) Had left.
Answer: B) Had you ever appeared.
Answer: A) Had seen.
Answer: C) Had
Answer: E) Had been-were found.
Answer: C) Had finished.
Answer: A) Done
Answer: A) Had entered-argued.
Answer: A) Couldn't
Answer: B) Had completed.
Answer: B) Had already seen.
Answer: C) Had left.
Answer: B) He began to run after he had seen the cat.
Answer: A) Had just washed/wanted.
Answer: B) Past Perfect Tense.
Answer: A) Past perfect tense.
Answer: A) Had read.
Answer: D) Had just finished.
Answer: A) Past Perfect.
Answer: B) Had discussed.
Answer: C) Had eaten.
Answer: C) Had/cleaned
Answer: C) Had been.
Answer: B) Had lived.
Answer: A) Had just left.
Answer: A) Had come[cos this happened BEFORE the other verb].
Answer: C) Eaten
Answer: A) Had studied.
Answer: B) I had slept when somebody knocked the door.
Answer: A) Had informed.
Answer: A) Had never felt.
Answer: D) Hadn't been used.
Answer: C) Had read.
Answer: B) Had fixed.
Answer: D) Was
Answer: A) Had
Answer: B) Had sent.
Answer: A) Yes, they had.
Answer: A) Past perfect.
Answer: A) Had never seen.
Answer: B) Had
Answer: B) Had played.