In the years following an eight-cent increase in the federal tax on a pack of cigarettes, sales of cigarettes fell ten percent. In contrast, in the year prior to the tax increase, sales had fallen one percent. The volume of cigarette sales is therefore strongly related to the after-tax price of a pack of cigarettes.

The argument above requires which of the following assumptions?

1. During the year following the tax increase, the pretax price of a pack of cigarettes did not increase by as much as it had during the year prior to the tax increase.

2. The one percent fall in cigarette sales in the year prior to tax increases was due to a smaller tax increase.

3. The pretax price of a pack of cigarettes gradually decreased throughout the year before and the year after the tax increase.

4. For the year following the tax increase, the pretax price of a pack of cigarettes was not eight or more cents lower than it had been the previous year.

5. As the after-tax price of a pack of cigarettes rises, the pretax price also rises.

Why chose D not E

这是一类很经典的题

其中的关系是：销量，税前价格，税后价格

题目说加税以后销量变化，因此销量和税后价格相关联，假设是税前价格不变。

试想：如果谁提高了8cent但税前价格又降低了8cent，那么售价不是没变吗？

 这是道很经典的取非削弱类假设题

取非之后，说税前的价格少了8美分，个么即使加了8美分的税，价格相当于也没变，削弱，所以正确

1.       T-9-Q4.
            

In the years following an eight-cent increase in the federal tax on a pack of cigarettes, sales of cigarettes fell ten percent. In contrast, in the year prior to the tax increase, sales had fallen one percent. The volume of cigarette sales is therefore strongly related to the after-tax price of a pack of cigarettes.

每包香烟的税增加8分的哪一年，销售量下滑10％。

在增税之前的那一年，销售量下滑了1％。

à
        香烟的销售量和每包香烟的税后价格高度相关。

（基本假设：增加的这8分，会让今年的税后价格较去年高）

The argument above requires which of the following assumptions?

1. During the year following the tax increase, the pretax price of a pack of cigarettes did not increase by as much as it had during the year prior to the tax increase.
                   （前一年的税前价格增加较多，今年的税前价格增加较少，则不知增加8分的税后价格是增加还是减少，因此不能做成本论之结论）

2. The one percent fall in cigarette sales in the year prior to tax increases was due to a smaller tax increase.（支持结论，而非结论之基本假设）

3. The pretax price of a pack of cigarettes gradually decreased throughout the year before and the year after the tax increase.（税前价格逐年降低，则不知税后的价格是增加还是减少，因此不能做成本论之结论）

4. For the year following the tax increase, the pretax price of a pack of cigarettes was not eight or more cents lower than it had been the previous year.（如果在增加8分之前的税前价格就比原来的税前价格低了八分或更低，则即使增税八分，税后价格还是比较低，所以要排除这个就是这个因果关系的基本假设）

5. As the after-tax price of a pack of cigarettes rises, the pretax price also rises.（税后价格增加，税前价格也同时增加，无法确定这个增加是由税所引起的，还是由原本的价格所引起的，所以无法确定税收影响销售额之因果关系。）

----------1% ↓sales----------------------8 cents↑federal tax-----------10%↓sales----------------------- à时间轴（tax与sales关系）

结论sales与after-tax price有联系，猜想à需要架桥，连接federal tax与after-tax price的关系

A：
            升tax以后pretax price的上升
            ≤ 升tax以前pretax price的上升，就是说没有提高tax以前反而price上升的更多（经济学常识àprice提高，sales下降），那么应该之前的sales更小，也就是降幅应该更大，与原文仅仅1%降幅矛盾，削弱（注意：文章并没有说tax升高了price一定会升高，这个不能和经济学原理一样当常识用）

B：
            无关，没有说price

C：
                pretax price在提高tax之前和之后都逐渐下降了，那么sales应该上升，但是原文都下降了，削弱

D：
            提高tax以后pretax price不会比前年低的超过8 cents，比如前年10 cents，今年≥2 cents。那么tax上升了8 cents，price下降的少于8 cents，所以after-tax price还是涨价了，sales下降。加强。如果取非，那就是说今年pretax price降低的比提高的tax还高，那么cigarette价格其实是降低了。Sales应该升高才对，而原文是sales降低。削弱。D选项不取非加强，取非削弱，很好的假设。

E：
            税后价格和税前价格的关系，无关