概述 1
Unit One 3
Unit Two 5
Unit Three 8
Unit Four 10
Unit Five 13
Unit Six 16
Unit Seven 19
Unit Eight 22
Unit Nine 25
Unit Ten 28
Unit Eleven 31
Unit Twelve 34
Unit Thirteen 37
Unit Fourteen 40
Unit Fifteen 43
Unit Sixteen 47
Unit Seventeen 50
Unit Eihgteen 53
答案 123
词汇表 131
录音文本 156