1 cave

2 shores

3 hill

4 desert

5 forest

6 waterfalls

7 valley

8 lake

9 cliffs

10 mountains

46 As he was making lunch, he felt ill

47 While I was staying in Hai Phong, I saw her

48 While I was having lunch, there was a knock at the door

49 While she was looking for a job, she got a scholarship from the university 

50 As the band were playing their first song, the lights went out

41 B

42 A

43 A

44 B

45 A

36 A

37 D

38 C

39 B

40 C

11 C

12 A

13 C

14 D

15 A

16 B

17 B

18 A

19 C

20 B

21 B

22 A

23 B

24 D

25 A

26 A

27 D

28 C

29 A

30 D

31 B

32 A

33 C

34 D

35 B