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.