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. (答案)
(D0The 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.
答案C中说飞机不是freewheel,可文中已提到过飞机是freewheel,难道直接反对前提也可以么??还是为了选择个相对来说更正确的就只能选C了,可反对前提也是很严重的错误啊……有谁思考过这个问题么？？帮帮忙吧！THX
（有一种解释是说：文中的freewheel指没有轨道的，而C中的freewheel指起点与终点不固定的，所以C没有反对前提。可我没办法被这种说法说服，太牵强了……因为文中的freewheel和C中的freewheel看上去太一样了）
waiting…………
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. (答案)
(D0The 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.
答案C中说飞机不是freewheel,可文中已提到过飞机是freewheel,难道直接反对前提也可以么??还是为了选择个相对来说更正确的就只能选C了,可反对前提也是很严重的错误啊……有谁思考过这个问题么？？帮帮忙吧！THX
（有一种解释是说：文中的freewheel指没有轨道的，而C中的freewheel指起点与终点不固定的，所以C没有反对前提。可我没办法被这种说法说服，太牵强了……因为文中的freewheel和C中的freewheel看上去太一样了）
你再仔细看一下，题中并没有说飞机是freewheel.
原文论点：the plane, can fly anywhere. The train would be a fixed linear system. Thus a sufficient market for the train will not exist.
如何反驳呢？
(A)Cars, buses, and planes require the efforts of drivers and pilots to guide them, whereas the train will be guided mechanically. -都需要司机。能够反驳，但未必是最有力的。
(B)Cars and buses are not nearly as fast as the high-speed train will be. -没有提到飞机的事情，反驳不够有力。
(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. (答案) -飞机也不是fly anywhere.而且去机场相比于去火车站更不方便。
(D0The high-speed train line cannot use currently underutilized train stations in large cities. 高速铁路不能直接用现在的火车站-支持原文论点了。
(E)For long trips, most people prefer to fly rather than to take ground-level transportation.-支持原文观点
从中选择最有力的，那只能在A,B,C中选，而C相对更好，直接攻击了fly anywhere.
(E)For long trips, most people prefer to fly rather than to take ground-level transportation.
为什么不能反对前提！！！
好像卡布奇诺L在别的帖子中也提到过这个问题！
我认为没有什么问题啊！反对前提是逻辑批判中一个重要的手段啊!难道GMAT要另辟蹊径？当然批判是要有逻辑性的批判。
就这道题而言，前提是飞机是free-wheel system，就像cares和buses一样。答案是说飞机其实并不是Free-wheel system，因为飞机是要机场的，而且这个机场不如高铁方便。这样就非常逻辑的推翻了题目中的前提。
有什么问题吗？
不逻辑性地推翻前提自然是错的，逻辑性地推翻前提不知道到底有什么问题！是不是新东方的老师说的，怎么好多人谈到这一点？！有没有OG的题目可以作为佐证的？能不能告诉本人。
这就像说，A的英语不错，所以他GMAT绝对能考很好。要想推翻这个推断，当然可以说并不是所有英语好的人都可以考好GMAT。难道不可以说：呵呵，其实有充足的证据表明A的英语并不是很好。而且英语不好是不可能考好GMAT的，所以A也考不好GMAT！
感谢楼上两位的回答！
TO：waterteller
这个不能反对前提的理论不知是谁最早提出的,但在上新东方的课程的时候确实是提到过这点,也就是不能反对文章前提.当然了,新东方也不是万能的,并不是说的什么都100%正确.但如果如楼上您所说,前提:A的英语好,结论:A能考好GMAT,削弱:A的英语不好,那前提启不是就白提出了么?!总觉得这样的削弱很不舒服……就像说：我喜欢吃香蕉，所以我吃了，削弱是我压根就不喜欢吃。这样感觉上会怪怪的啊？！
暂时不说这个问题，可否再告诉我几道OG中这种反对前提的逻辑题呢？谢谢！！！
1．同意不能反对前提
2．两个freewheel的问题
一种解释是说：文中的freewheel指没有轨道的，而C中的freewheel指起点与终点不固定的，所以C没有反对前提。可我没办法被这种说法说服，太牵强了……-> 同意，十分牵强。
我的理解：文中的freewheel和C中的freewheel是一个概念。但是，文中aircraft和C中的plane有差异。Aircraft是飞行器的统称，假设包括直升飞机，战斗机，热气球，飞毯等，是没有轨道，起点终点都不固定的；但C中的plane指的是民用航班（和高速火车对比肯定是民航），是起点与终点固定的。飞机本身可以不受起点终点的限制，但一旦成为民航，就有这个限制，也就不是freewheel了。所以plane和高速火车比，就没有这个优势了，结论就被削弱了。
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