21. When I (arrive) ____________ this house, he still (sleep) ____________. 22. The light (go out) ____________ when we (have) ____________ dinner. 23. Bill (have) ____________ breakfast when I (stop) ____________ at this house this morning. 24. As we (cross) ____________ the street, we (see) ____________ an accident. 25. Tom (see) ____________ a serious accident while he (stand) ____________ at the bus stop. 26. While my father (read) ____________ the newspaper, I (learn) ____________ my lesson and my sister (do) ____________ her homework. 27. The children (play) ____________ football when their mother (come) ___________ back home. 28. The bell (ring) ____________ while Tom (take) ____________ a bath. 29. I (be) ____________ tired because I (work) ____________ all day yesterday. 30. While I (walk) ____________ along the street, I (see) ____________ an old friend. 31. How long ________you (study) ____________ English? For 5 years. 32. I (wait) ____________ for two hours, but she (not come) ____________ yet. 33. They (live) ____________ in Ho Chi Minh City since 1975. 34. She (read) ____________ all the books written by Dickens. How many books you (read) ____________? 35. He (not, be) _____________ here since Christmas, I wonder where he (live) ___________ since then. 36. Jack (go) ____________ to Paris for a holiday. He ______never (be) ____________ there. 37. You (sleep) ____________ so far? I (ring) ____________ the bell for the last twenty minutes. 38. He (write) ____________ a novel for two years, but he (not/ finish) ____________ yet. 39. Mary (lose) ____________ her hat and she (look) ____________ for it until now. 40. I (see) ____________that film several times because I like it.