OG13 CR112 请NN指教下

shaoshiever

112. The difficulty with the proposed high-speed train line is that a used plane can be bought for one-third the price of the train line, and the plane, which is just as fast, can fly anywhere. The train would be a fixed linear system, and we live in a world that is spreading out in all directions and in which consumers choose the free-wheel systems (cars, buses, aircraft), which do not have fixed routes.Thus a sufficient market for the train will not exist. Which of the following, if true, most severely weakens the argument presented above? (A) Cars, buses, and planes require the efforts of drivers and pilots to guide them, whereas the train will be guided mechanically. (B) Cars and buses are not nearly as fast as the high-speed train will be. (C) Planes are not a free-wheel system because they can fly only between airports, which are less convenient for consumers than the high-speed train’s stations would be. (D) The high-speed train line cannot use currently underutilized train stations in large cities. (E) For long trips, most people prefer to fly rather than to take ground-level transportation. 这道题之前也有讨论过，但没有结果，这道题的正确答案是C。其实在选择的时候根据感觉也一下子就能选出来，但知这C是不是直接说文中premise的信息有错误呢？削弱不是不应该说premise本身的错误吗？ 这里怎么回事呢？

wwxavier

刚刚看GMAT，我不知道我说的对不对，我感觉楼主过于专注于所谓的逻辑链而没有认识到这段话到底在讲什么。
我读完短文给我的意思就是作者在拿飞机和火车作比较，最后火车输了。题目问削弱，那就找飞机并不能赢的选项就是。
前提1：火车比飞机贵
前提2：顾客选择free-wheel systems. 我和楼主一样开始一直纠结于那个括号里的东西，好好读读感觉作者的意思是顾客去选择给个括号貌似有举例的意思，但并没有说aircraft就一定是free-wheel systems。
结论：火车不行!
最近在看Helr的逻辑方法或许能让你感觉深一些。
这个题是因果模式推论
两个破题点
1. 因果概括问题
2.干扰因素问题
答案必须说出一个“因”的可导致结论可信度发生变化的特点
或者
直接涉及到因果之间的联系。
C选项是因的一个特点，它直接导致了结论（也就是果） 的可信度变化。

shawnshao

shaoshiever 发表于 2013-9-19 01:13
谢谢你的回答，但能告诉我题目说 the free-wheel systems (cars, buses, aircraft)，c说的是 Planes are  ...

C不是直接驳斥了你的前提2吗

shaoshiever

shawnshao 发表于 2013-9-18 01:43
The argument says the train is not as good as flight.

C said flight doesn't help either.

谢谢你的回答，但能告诉我题目说 the free-wheel systems (cars, buses, aircraft)，c说的是 Planes are not a free-wheel system，不就和文章说的不一样了吗~我的理解是前提是1.飞机便宜而且飞得快2是 free-wheel systems四通八达 结论是火车没市场，请问哪里错了，谢谢啦

shawnshao

The argument says the train is not as good as flight.

C said flight doesn't help either.

So C weakens the argument.

Got it?

shaoshiever

薄荷0816 发表于 2013-9-17 16:35
http://forum.chasedream.com/thread-837431-1-4.html
我发现了这个~

弱弱的说一句其实我就是没看懂这个帖，才发帖的，那个贴里讨论到最后就变成我们还是不纠结这个问题比较好。所以。。。。。。

薄荷0816

shaoshiever 发表于 2013-9-17 16:02
谢谢你的回答，那啥脑子没转过来，题目说 the free-wheel systems (cars, buses, aircraft)，c说的是 Pla ...

http://forum.chasedream.com/thread-837431-1-4.html
我发现了这个~

薄荷0816

shaoshiever 发表于 2013-9-17 16:02
谢谢你的回答，那啥脑子没转过来，题目说 the free-wheel systems (cars, buses, aircraft)，c说的是 Pla ...

我也不太明白了，C反驳的就是虽然飞机没有轨道但是它也不是那么方便因为需要机场啥的。其实根本不用加那句 Planes are not a free-wheel system，对吧。。。

shaoshiever

薄荷0816 发表于 2013-9-17 14:33
个人这么理解的，题目中说的是the free-wheel systems (cars, buses, aircraft), which do not have fixed ...

谢谢你的回答，那啥脑子没转过来，题目说 the free-wheel systems (cars, buses, aircraft)，c说的是 Planes are not a free-wheel system，不就和文章说的不一样了吗~我的理解是前提是1.飞机便宜而且飞得快2是 free-wheel systems四通八达 结论是火车没市场，请问哪里错了，谢谢啦

薄荷0816

个人这么理解的，题目中说的是the free-wheel systems (cars, buses, aircraft), which do not have fixed routes. 也就是把do not have fixed routes定位成了the free-wheel systems （主要是为了和火车相比较）。所以C中反驳的我觉得并不是前提，而是the free-wheel systems不仅仅指轨道，还有别的方面，这样就把这个定义扩大了，那这个推导人们喜欢the free-wheel systems所以铁路不存在就不成立了。
感觉说的有点乱。。。。。不知道你能理解不