. Bài tập ví dụ: 1. The storm destroyed the sandcastle that we (build) A. Had been building B. Had built C. Built D. Building 2. He (not / be) to Cape Town before 1997. A. Not be B. Had not be C. Had not been D. Had been 3. We (sleep) for 12 hours when he woke us up. A. Had been sleeping B. Had slept C. Slept 4. They (wait) at the station for 90 minutes when the train finally arrived. A. Had waited B. Had been waiting C. Had wait D. Waited 5. When she went out to play, she (do / already) her homework. A. Had already done B. Have already done C. Already done D. Has already done 6. My brother ate all of the cake that our mum (make). A. Had made B. Had been making C. Made 7. The doctor took off the plaster that he (put on) six weeks before. A. Has put on B. Had put on C. Had been putting on 8. We (look for) her ring for two hours and then we found it in the bathroom. A. Had looked B. Had looking C. Had been looking D. Looked 9. (you / finish) your homework before you went to the cinema? A. Have you finished B. Had you finished C. Did you finished 10. (why / you / clean) the bathroom before you bathed the dog? A. Why had you cleaned B. Why you had cleaned C. Why cleaned you had 11. (you / have) breakfast before you came here? A. Had had you B. Had you had C. Did you have D. Do you have 12. (she / find) a place to stay when she went to Boston? A. Had she found B. Had she find C. Did she find 13. (where / she / live) before she moved to Chicago? A. Where did she live B. Where had she lived C. Where had she live 14. I (not / walk) for a long time, when it suddenly began to rain. A. Did not walk B. Had not been walking C. Had not walked D. Walked 15. How long (learn / she) English before she went to London? A. Had she learned B. Had she been learning C. Had she learn D. She leared 16. Frank Sinatra caught the flu because he (sing) in the rain too long. A. Had been singing B. Had sang C. Had sung D. Had singing 17. He (drive) less than an hour when he ran out of petrol. A. Had been driving B. Had driving C. Had drived D. Drived 18. They were very tired in the evening because they (help) on the farm all day. A. Had been helped B. Had been helping C. Helped 19. I (not / work) all day; so I wasn't tired and went to the disco at night. A. Had not been working B. Had worked C. Had not worked D. Had not been worked 20. They (cycle) all day so their legs were sore in the evening. A. Had been cycle B. Had been cycling C. Had cycled D. Had been cycled