请各位帮忙解析下OG11的122题

xunxun365

122. When people evade income taxes by not declaring taxable income, a vicious cycle results. Tax evasion forces lawmakers to raise income tax rates, which causes the tax burden on nonevading taxpayers to become heavier. This, in turn, encourages even more taxpayers to evade income taxes by hiding taxable income.

The vicious cycle described above could not result unless which of the following were true?

(A) An increase in tax rates tends to function as an incentive for taxpayers to try to increase their pretax incomes.

(B) Some methods for detecting tax evaders, and thus recovering some tax revenue lost through evasion, bring in more than they cost, but their success rate varies from years to year.

(C) When lawmakers establish income tax rates in order to generate a certain level of revenue, they do not allow adequately for revenue that will be lost through evasion.

(D) No one who routinely hides some taxable income can be induced by a lowering of tax rates to stop hiding such income unless fines for evaders are raised at the same time.

(E) Taxpayers do not differ from each other with respect to the rate of taxation that will cause them to evade taxes.



正确答案是（C），我选了（E）个人认为如果taxpayers的承受度上有差异，开始逃税的起点不同，那么增税不一定加重不逃税的人的负担。不知错在哪呢？正确选项（c）的英文意思我也没太明白。请大家给我指点指点(+.+)

sdcar2010

This is a necessary assumption question.  Use the negation method.

If you negate answer (C), you get:
When lawmakers establish income tax rates in order to generate a certain level of revenue, they DO allow adequately for revenue that will be lost through evasion.

If this is the case, there is no need for the lawmakers to raise income tax rates since they have already factored in such evasion when writing the tax code.  As such, the whole argument falls apart.  Therefore, answer (C) is a necessary assumption and the right answer.

kevin0214

其实楼主自己的分析已经说明了E的不对，题目问The vicious cycle described above could not result unless which of the following were true。正确答案必须是一个必要条件，也就是说，你对它取非的时候，原题的结论“必然”不成立！“不一定”不成立是不够的，E不是正确答案。

xunxun365

感谢sdcar2010和kevin0214的解答O(∩_∩)O