52. D. treat the environment => treated the environment
53. C. environmental (adj) => environment (n)
54. A. having been warn => having been warned
55. B. accused on => accused of
56. A. having deciding => having decided
57. B. harmful affects => harmful effects
58. D. help reduced => reduce
59. C. they start => they stared
60. C. started do => started to do
61. A. having cutting => having cut