Chọn thì thích hợp nhất để hoàn thành các câu sau: 28. The train ______ when I ______ at the station. A. already left / had arrived B. already had left / arrived C. left already / had arrived D. had already left / arrived 29. Everyone was asleep when the enemy _____________ A. had attacked B. attacked C. was attacking D. attacking 30. Don't make noise. My mother ________________with her friends. A. talked B. talks C. is talking D. was talking 31. She ______ the piano since she ______ ten years old. A. played / was B. has played / has been C. has played / was D. had played / was 32. Up to now, I _________________ a lot of information about her. A. learnt B. would learn C. learn D. have learnt 33. Mary ___________ in London for 15 years. A. lives B. was living C. is living D. has lived 34. We were disappointed that most guests ___________ when we arrived at the party. A. had left B. has left C. left D. leave 35. He never goes home before he ______ his work. A. finished B. has finished C. had finished D. finishing 36. Before cars ______, people ______ horses and bicycles. A. were discovered / had used B. has been discovered / have been using C. is discovered / using D. discovering / used