41. Our teacher usually ……………………(give) us many exercises.
42. He often ……………………(catch) a train to work.
43. The cat ……………………(catch) mouse.
44. They ……………………(plant) trees over there at the moment.
45. My old friend, Manh ……………………(write) to me twice a month.
46. What she says ……………………(be) true.
47. Where she ……………….…………………(buy) her breakfast every morning?
48. Bien ………….. often ……………………(not phone) to me.
49. Mrs. Green always ……………………(take) a bus to work. But now he ……………………(drive) to work.
50. Look! The ball ……………………(fall) down.