概述 1
Unit One 3
Unit Two 5
Unit Three 8
Unit Four 10
Unit Five 12
Unit Six 15
Unit Seven 17
Unit Eight 20
Unit Nine 23
Unit Ten 26
Unit Eleven 29
Unit Twelve 32
Unit Thirteen 34
Unit Fourteen 37
Unit Fifteen 40
Unit Sixteen 43
Unit Seventeen 46
录音文本 49
答案 100
词汇表 108