53,If I don't have a quiet room, I won't be able to do anything
54,It has rianed for an hour
55,She hasn't visited me for five years
56,If we don't hurry up, we will be late for the exam
57,How long have you learned English?
58,If you are careless, you may fall
59,We have lived here for fifteen years
60,We have become close friends for a long time
61,The last time we visited my grandparents was two months ago
62,Unless we try to save our sources of energy, it will soon end
63,Minh has collected stamps since 2000
64,I have never talked to a foreigner before
65,Today VTV3 has three interesting films
66,It's five years since my brother last met his best friend
67,Unless you keep your feet dry, you will catch a cold
68,Unless we try to save our sources of energy, it will soon end
69,If we use the car all the time, we will make the air dirty
70,If we don't leave now, we will miss the plane
71,I began studying English three years ago
72,Unless I leave now, I will miss my train
73,You must do your homework
74,If I don't have a modern robot, I won't be able to do everything myself
75,I haven't seen Ann since yesterday
