UNIT ONE 1
UNIT TWO 21
UNIT THREE 41
UNIT FOUR 59
REVIEW ONE (Unit1-Unit4) 76
UNIT FIVE 92
UNIT SIX 112
UNIT SEVEN 131
UNIT EIGHT 151
REVIEW TWO (Unit5-Unit8) 174
UNIT NINE 190
UNIT TEN 211
UNIT ELEVEN 231
UNIT TWELVE 250
REVIEW THREE (Unit9-Unit12) 269
UNIT THIRTEEN 285
UNIT FOURTEEN 304
UNIT FIFTEEN 321
UNIT SIXTEEN 340
REVIEW FOUR (Unit13-Unit16) 357
APPENDIXⅠAbbreviations and Symbols 373
APPENDIXⅡA List of Irregular Verbs 375
APPENDIX III Phrases and Expressions 379
APPENDIX IV Proper Nouns 384
APPENDIX V Vocabulary 386