7.美国经济调查
　　还有个阅读讲什么最近美国经济调查的，Cox这个学者认为家庭(注意是家庭)收入比多少多少年前才增长了一点点
　　有个人说这个结果不靠谱，光看了家庭收入的增长，没看见家庭收入发展前景的增长，说什么自己做了个研究，研究了10年间吧人们收入 的变化，开始最低的那15个人后来只有5%还是最低，其他95%都增长了，有几个还到了前几名，然后就用个人收入的增长类比前面的家庭收入调查
　　又有一个哥们出来说，你这个也不对(疯了~~~~~)，你类比错误，因为它包括相当一部分在最初做兼职的学生，这些学生在毕业后，全职工作的收入自然会有明显增长，而那些typical family 一般至少有一个成员是全职工作的，他们的收入变化就不会这么明显。
　　study of income mobility. The study found that after 5 years, 5% lowest income people will not stay at the bottom. As a result, the income of mobility is healthy. However, the study commits mistakes because it include teenage part-time workers, after 5 years, they are more likely to get full-time job and higher salary.
　　出题都在第二段
　　有一个问举大学生业余工作的例子说明什么，答案是和family的情况对比,是第二个人用来反驳开始那个人的说法(大学生业余工作工资低，毕业挣钱立马高了;family变化小)
　　1、第二个人指出了第一个人的什么错误啊
　　2、 第一个人最concern什么啊。。
　　考古：
　　V2
　　Income mobility in the U.S. is only moderate. Most people see their incomes rise with age, but at some point they usually hit a plateau in the income distribution, where they fluctuate mildly for the rest of their careers. The Hubbard study of income mobility, commonly cited by conservatives, used an extremely biased sample of unusually successful American families. Its results are therefore invalid. Allowing a society of extreme income inequality, even with high mobility, would raise child poverty, because most parents are young and incomes are lowest during young adulthood 。Many conservatives admit that incomes in the U.S. are highly unequal, but claim they are highly mobile as well. That is, people tend to rise and fall considerably on the income scale throughout the course of their lives, producing a lifetime average which is much closer to everyone else. Furthermore, this mobility tends to be upward; incomes generally rise with age. Hence, inequality is not as unfair as liberals claim