IV
36. Soil pollution can make plants die.
37. What do these three rs stand for?
38. If we all use this kind of bag ,we 'll help to protect the environment.
39. we should find creative ways to reuse our old iteams before throwing them away.
40. If the river is not poluted there will be more fish.
V.
41. Will.
42. Will 
43. Might
44. Won't.
45. Will.
46. Will.
47. Will.
48. Will.
49. Might.