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1·CPOs is younger, less white, and poorer than the average American.

只使用手机一族大多是年轻人，很少白人且生活水平低于美国人平均水平。

2·At the national level it is easy enough, though expensive, to account for this by surveying CPOs and including them in the sample in proportion to their share of the population.

尽管昂贵，但从国家水平来看，民意调查如按CPOs在总人口中所占的比例计算，调查就会很容易。