UNIT 1 1
Exercise 1 1
Exercise 2 3
Exercise 3 4
参考答案 7
UNIT 2 8
Exercise 1 8
Exercise 2 9
Exercise 3 11
参考答案 13
UNIT 3 14
Exercise 1 14
Exercise 2 15
参考答案 18
UNIT 4 19
Exercise 1 19
Exercise 2 20
Exercise 3 22
参考答案 25
UNIT 5 26
Exercise 1 26
Exercise 2 28
Exercise 3 30
参考答案 32
UNIT 6 33
Exercise 1 33
Exercise 2 35
Exercise 3 37
参考答案 39
UNIT 7 40
Exercise 1 40
Exercise 2 41
Exercise 3 44
参考答案 47
UNIT 8 48
Exercise 1 48
Exercise 2 50
Exercise 3 52
参考答案 55
UNIT 9 56
Exercise 1 56
Exercise 2 58
Exercise 3 60
参考答案 63
UNIT 10 64
Exercise 1 64
Exercise 2 66
Exercise 3 67
参考答案 69
UNIT 11 70
Exercise 1 70
Exercise 2 71
Exercise 3 73
参考答案 76
UNIT 12 77
Exercise 1 77
Exercise 2 79
Exercise 3 81
参考答案 83
UNIT 13 84
Exercise 1 84
Exercise 2 86
Exercise 3 87
参考答案 90
UNIT 14 91
Exercise 1 91
Exercise 2 93
Exercise 3 95
参考答案 98
UNIT 15 99
Exercise 1 99
Exercise 2 100
Exercise 3 102
参考答案 105
UNIT 16 106
Exercise 1 106
Exercise 2 108
Exercise 3 110
参考答案 113
UNIT 17 114
Exercise 1 114
Exercise 2 116
Exercise 3 118
参考答案 121
UNIT 18 122
Exercise 1 122
Exercise 2 124
Exercise 3 126
参考答案 129
UNIT 19 130
Exercise 1 130
Exercise 2 132
Exercise 3 134
参考答案 138
UNIT 20 139
Exercise 1 139
Exercise 2 141
Exercise 3 143
参考答案 145