意思基本上都明白了，就是不晓得为什么选C，帮帮我吧！

zhongweiwei

The U.S. census is not perfect: thousands of Americans probably go uncounted. However, the basic statistical portrait of the nation painted by the census is accurate. Certainly some of the poor go uncounted, particularly the homeless; but some of the rich go uncounted as well, because they are often abroad or traveling between one residence and another.

Which of the following is an assumption on which the argument above depends?

(A) Both the rich and the poor have personal and economic reasons to avoid being counted by the census.

(B) All Americans may reasonably be classified as either poor or rich.

(C) The percentage of poor Americans uncounted by the census is close to the percentage of rich Americans uncounted.

(D) The number of homeless Americans is approximately equal to the number of rich Americans.

(E) The primary purpose of the census is to analyze the economic status of the American population.

答案是C

xuyongxxx

这段话的一个观点是：尽管很多人都没有被统计，但是统计数字反映出来的特征还是准确地。

然后进一步解释，为啥呢：因为——虽然穷人可能没有被统计、从而导致统计数字失真，但是富人同样也有可能没有被统计。

这样，如果我们用统计数字来刻画美国的穷富比例的话，由于两种人都有可能没有被统计，所以，最终的推断可能和真实情况差不多。

但是，实际上，这种推断需要穷人没被统计的数量和富人没被统计的数量差不多，

否则，前面提到的“统计数字反映出来的特征还是准确地”就不对了。

不知道说明白没有...

zhongweiwei

我基本上明白了你解释的意思了，你解释应该是对的。我对于这个“the basic statistical portrait ”的概念实际还是比较模糊的，它是指富人和穷人的一种比例？另外这种portrait中除了穷人和富人之外有没有中产阶级呢？如果有中产阶级的话，命题似乎有问题啊。

xuyongxxx

“the basic statistical portrait ”俺也不是很明白，估计就是一些简单的描述性统计：谁比谁多，谁比谁少，谁占多少比例之累的吧

不是学人口学的，估计学这个的能解释明白。

so...