IV.

31. You're tired although-> because you stayed up too late to watch TV last night. 

32. Tuan sighed sad-> sadly when he heard that he failed the test.

33. Don't speak english with him ; he hardly not know-> knows any English.

34. 90 percent of earthquakes occurs->occur around the Pacific Rim.

V.

35. Fuel consuming can be cut down by having fewer cars on the roads.

36. Many chemicals have a disastrous effect on the environment.

37. Luckily, the typhoon didn't cause any damage on the village.

38. The next stage in the development of television is interactive TV.

31, B. although=> beacause

32, B. sad=> sadly

33, (Mình nghĩ là gạch chân thiếu)

     D. hardly not know => hardly know

34, C. occurs => occur

35, consumption

36,  disastrous

37, Luckily

38, development