文档介绍：UNIT 1
1. B
2. C
3. C
4. B
5. D
6. C
7. C
8. the transport of dangerous substances
9. one of the 21 transfer stations
10. the chemicals-collection station
47. D
48. H
49. B
50. I
51. L
52. O
53. F
54. N
55. C
56. M
57. C
58. C
59. A
60. B
61. D
62. D
63. C
64. D
65. B
66. A
67. C
68. B
69. A
71. A
72. D
73. B
74. B
75. D
76. C
77. B
78. C
79. A
80. D
81. C
82. C
83. B
84. A
85. C
86. D
UNIT 2
1. D
2. B
3. C
4. D
5. A
6. D
7. A
8. 170 miles
9. one foot
10. flood-control dams
57. B
58. B
59. D
60. C
61. A
62. A
63. B
64. D
65. B
66. C
67. C
68. A
69. C
71. D
72. B
73. A
74. C
75. A
76. A
77. D
78. D
79. B
80. C
81. C
82. D
83. A
84. B
85. B
86. C
UNIT 3
1. B
2. C
3. D
4. A
5. B
6. C
7. B
8. the early 1900s
9. maximal performance
10. so much anxiety
57. B
58. C
59. D
60. A
61. B
62. A
63. C
64. B
65. C
66. C
67. C
68. A
69. D
70. B
71. C
72. A
73. B
74. D
75. A
76. A
77. B
78. D
79. D
80. A
81. C
82. B
83. C
84. D
85. D
86. A
UNIT 4
1. C
2. B
3. C
4. D
5. D
6. B
7. A
8. Medium size or small
9. keen sense of smell
10. it to “come”
57. D
58. B
59. C
60. C
61. A
62. D
63. C
64. D
65. B
66. C
67. A
68. B
69. D
70. A
71. C
72. D
73. B
74. A
75. C
76. B
77. C
78. A
79. B
80. D
81. D
82. D
83. A
84. D
85. D