LSAT2-1 请教

friday

LSAT2-1

13. If retail stores experience a decrease in revenues during this holiday season, then either attitudes toward extravagant gift-giving have changed or prices have risen beyond the level most people can afford. If attitudes have changed, then we all have something to celebrate this season. If prices have risen beyond the level most people can afford, then it must be that salaries have not kept pace with rising prices during the past year.
Assume the premises above to be true. If salaries have kept pace with rising prices during the past year, which one of the following must be true?
(A) Attitudes toward extravagant gift-giving have changed.
(B) Retail stores will not experience a decrease in retail sales during this holiday season.
(C) Prices in retail stores have not risen beyond the level that most people can afford during this holiday season.
(D) Attitudes toward extravagant gift-giving have not changed, and stores will not experience a decrease in revenues during this holiday season.
(E) Either attitudes toward extravagant gift-giving have changed or prices have risen beyond the level that most people can afford during this holiday season.


为什么B 不对呢, 用逆反命题做, 再前推一步,就可以得到B呀?
工资与价格同步,- 价格在承受范围之内--- retail stores will not experience a decrease

dorbear

这里面有两个原因一个结果：

结果：retail stores experience a decrease in revenues during this holiday season
     原因1：attitudes toward extravagant gift-giving have changed；
     原因2：prices have risen beyond the level most people can afford；而原因2产生于：
            原因21：salaries have not kept pace with rising prices during the past year.

通过逆否，只能是原因21不成立，所以原因2不成立。而我们不知道原因1成立与否，所以只能推论到这里。MUST TRUE 的推论题必须保证推论成立不需要任何额外的假设条件。

个人理解万岁！

雪落无声

原因2不成立为什么不能推出原因1成立呐？原文有either  or 说明必有一个原因成立才导致结果。

我选A，哪里错了？

freedownload

我觉得是C

番茄炒蛋

感觉c是最简练的逆反命题

还有一个问题，多多熊的积分怎么这么低了啊，你是不是到了999999，然后。。。。。

呵呵，我记得你以前分很高的啊

philikittist

题干给的前提：

1. 收入下降->（态度改变）or （价格离谱）

    【逆否命题：（态度没改变）and （价格不离谱）->收入没下降】

2.价格离谱->工资不配套    【逆否命题：工资配套->价格不离谱】

现在如果已知：工资配套

可以得到C：价格不离谱。

但要推出B（收入没下降）必须还要有条件（态度没改变）。