6.B economic

7.B isn't she

8. B to visit

9.C to lock

10.D because of + cum danh tu

11.A who + V: nói về người

12.C hadn't gone

13.B was

14.A themselves

15.by (learn by heart : học thuộc lòng)

16.B missed

17.B although + mệnh đề

18.A suit 

19.at (be good/ bad at sth : giỏi/dở về cái gì)

20.B on

21.C between ->in

22.B to go ->going

23.A rain -> rains

24.C attracts -> attracting

25.C to raise -> raising

26. B orbit

27.A consists

28.A produce

29.C possible

30.D sun

31D the smallest

32B of

33D sky

34D contains

35B are

36. cooked

37. goes (everyday : HTD)

38. are playing (now: HTTD)

39. did/go

40.bring

41.The girl, who lived next door to us ,is very friendy

42. Mr Brown asked me what my name was

43. It is necessary to learn English

44. In spite of his broken leg, ...........

= in spite of the broken leg,.............

45. Unless someone put the coal in, the fire will go out.