Mình cần gấpp lắm giúp mình vớii 21. The teacher (do)____________research in the library right now. 22. He usually (learn)________________his lesson in the evening but last night when I (get)___________to his house, he (listen)______________to the radio. 23. The earth (depend)_________________on the sun for its heat and light 24. Up to now, the teacher (give)________________our class five tests. 25. Some animals (not eat)_____________during winter. 26. When she (see)___________a snake at her feet yesterday, she (scream)__________________. 27. Yesterday when I (see)___________him, he (sit)___________asleep in an armchair. 28. Please be quiet! I (work)________________. 29. He (live)_______________near our house, but we (not see)_________________him very often. 30. I (not/ send)________________the parcel until I hear from you. 31. Long ago, my younger brother often (cry)_______________. 32. Last Saturday while Sandy (clean)_____________out the attic, she (find)_______________her grandmother’s wedding dress. 33. She (be)_______________ill for several months. 34. Mr Green (buy)___________a new tractor last month. 35. He thinks that it (rain)______________tonight. 36. He (lose)_____________his job last month and since then he (be)___________out of work. 37. ___________you (finish)___________your homework? 38. I don’t smoke while I (drive)______________a car. 39. Henry (eat)_______________a snack at midnight last night. 40. When he (receive)_______________the photographs, he will show them to you. 41. The leaves (fall)__________________from the trees when autumn (come)_________________. 42. I (receive)________________twenty cards so far. 43. In the 19th century, it (take)________ two or three months to cross North America by covered wagon. The trip (be)________ very rough and often dangerous. 44. I (go)_____________ to the same barber since last year. 45. Ask her to come and see me when she (finish)_______ her work.