练习答案和参考译文 1
UNIT ONE 1
目录 7
教学要求 7
Teaching Suggestions 9
UNIT TWO 10
UNIT THREE 20
UNIT FOUR 31
UNIT FIVE 40
UNIT SIX 49
UNIT SEVEN 60
UNIT EIGHT 70
UNIT NINE 79
UNIT TEN 90
UNIT ELEVEN 103
UNIT TWELVE 113
UNIT THIRTEEN 121
UNIT FOURTEEN 130
UNIT FIFTEEN 140
UNIT SIXTEEN 148
UNIT SEVENTEEN 156
UNIT EIGHTEEN 167
UNIT NINETEEN 177
UNIT TWENTY 187