Unit One Growing Up 1
Unit Two Friendship 12
Unit Three Understanding Science 22
Unit Four The American Dream 33
写作训练 43
Test One （Units 1～4） 52
Unit Five Work to Live or Live to Work 60
Unit Six Romance 70
Unit Seven Animal Intelligence 82
Unit Eight Educational Problems 93
写作训练 104
Test Two （Units 5～8） 113
参考答案 122