从两道神似的题看ETS出题规律

下面这一题是我从逻辑讨论区里翻出来的2004年贴的一题，当时的讨论很激烈，最后比较统一的答案是A

The cost of flood damage since 1980 has been greater in areas that have adopted flood-control measures than in those that have not. Thus, flood-control projects are expensive engineering mistakes and a substantial waste of resources.
Which of the following, if true, would be most damaging to the argument above?
(A)Those areas that had not suffered flood damage before 1980 are the only ones that have not adopted flood-control measures
(B)Since 1980, those areas that have taken flood-control measures have suffered greater flood damage than they did in the previous decade
(C)The cost of flood damage has increased every year since 1980
(D)Faulty engineering has not been the only cause of the failure of flood-control projects
(E)The amount of rainfall since 1980 has been substantially greater than normal

下面是我在GMAT备考时做的一道逻辑题，答案也是A

Critics of sales seminars run by outside consultants point out that since 1987, revenues of vacuum cleaner companies whose employees attended consult ant-led seminars were lower than revenues of vacuum cleaner companies whose employees did not attend such seminars. The critics charge that for vacuum cleaner companies, the sales seminars are ill conceived and a waste of money.

Which of the following, if true, is the most effective challenge to the critics of sales seminars?

(A)   Those vacuum cleaner companies whose sales were highest prior to 1987 are the only companies that did not send employees to the seminars

(B)    Vacuum cleaner companies that have sent employees to sales seminars since 1987 experienced a greater drop in sales than they had prior to 1987

(C)    The cost of vacuum cleaner sales seminars run by outside consultants has risen dramatically since 1987

(D)   The poor design of vacuum cleaner sales seminars is not the only reason for their ineffectiveness

(E)    Since 1987 , sales of vacuum cleaners have risen twenty percent

敲完这题，发现这两题简直可以说是一模一样，仔细看选项的结构，就可以一目了然。

上面那一题，当时看了讨论帖，争议初步集中在A，B，E三个选项中，现在我把这两题的结构和内容作一个总结，大家可以再来体会一下：

文章：从XX年以后，进行了一项X操作的X实体比不进行X操作的X实体情况要更坏，结论是：进行X操作不好。问削弱。

A．那些在XX年以前情况更好/最好的X实体时是唯一没有进行X操作的实体

B．自从XX年以后，进行X操作的X实体情况比以前更坏了

E．自从XX年以后，情况（两实体比较的内容，但是没有指明是哪个实体的情况）更好了/更突出了。

以上的结构大致就是这两题的共同之处，从选项看，A其实可以这样理解，既然情况更好的实体是唯一没有进行X操作的实体，那么也就是说，没有进行X操作的实体都是情况更好的/最好的，那么文章一开始的比较就是没有意义的，也就是削弱了文章的前提，自然推导出的结论就不成立了。

而B明显的是一个加强选项，它相当于把文章的前提中提到的事实再重复了一遍

E是一个无关选项，没有对前提进行任何削弱或加强，因为选项没有指向两个比较对象中的任一个，而是把两者比较的内容进行了一些事实性的叙述。

初来乍到，对于GMAT题的体会不太深刻，我也只能就事论事了，希望能对大家有所启发，如果有不足和错误，请指正！

看完你的解释,觉得两题A选项都对, 但是觉得第一题的B也对.

第一题题目推理是: 自从1980年以后,实行防洪措施的地区比没有实行防洪措施的地区损失还多, 所以防洪措施没用.

A 选项说80年以前, 没有遭受洪水的地区仅限于没有实行防洪措施的地区. 言下之意为只有实行防洪措施的地区才遭受洪水的地区. 再进一步推理: 实行防洪措施的地区本来就比没有实行防洪措施的地区更容易遭受洪水. 所以两地区inherently different,所以不能够用两地区比较的结果来评判防洪措施是否有效. 要是套用逻辑解题原则的话,应该就是削弱前提来削弱结论.

但是这里说的是1980年以前的事实,那么可不可能在80年以后不成立了呢? 那不就构不成法对了吗?

B选项说80年后, 实行防洪措施的地区遭受了比以前更大的洪水. 那么可不可以理解为: 在80年以前,在洪水不那么大的时候, 实行防洪措施的地区 实际上 有可能比没有实行防洪措施的地区 损失少呢, 从而证明实行防洪措施多少起了作用.

第二道题因为没有其他干扰选项, 觉得就A还可以.

觉得自己好像钻到了牛角尖,请高手点播.

谢谢

第一题的B明显不对。

推论本来就是装了那个X有可能导致damage更高。B应该是证明是这样。

而且楼上对B的翻译有问题。B是受到更大的洪水破坏，而不是更大的洪水。

那么这两题就都默认了在特定年份前后, 比较两者没有发生实质性改变. 还是觉得心里不踏实

谢谢两位的点评，对于第一题的疑问，建议mybluemoon 去看看这个贴http://forum.chasedream.com/dispbbs.asp?BoardID=24&ID=48747&replyID=&skin=1

里面有很多NN进行了解释，逻辑对于我来说还比较弱，对于这两题的解释只能到这个程度了，望高手看到此贴能够留下宝贵经验。

还有做题的时候我也发现其实ETS还有很多类似的神似题，大家不妨进行总结，这样，就可以提高做题速度了！！