54. C => environment
55. A => Having been warned (having + VpII)
56. C => accused of (bị buộc tội đã làm gì)
57. A
58. B harmful affects -> harmful effects.
59. D help + V: giúp đỡ làm cái gì
60. they start -> they started
61. C “start” + V-ing: bắt đầu làm gì đó
62. A
63. C Having dumped (having + VpII)
64. D treated the environment (having + VpII)
65. B
66. C
