GMAT逻辑解题思路举例解析，GMAT逻辑部分的试题，要求考生具备相当逻辑推理能力，因为慎密的解题思路才能够保证GMAT逻辑题目的做题正确率。
本文主要就“无关信息排除法”来锻炼考生的逻辑思维，下面是具体的例题：
Teenagers are often priced out of the labor market by the government-mandated minimum-wage level because employers cannot afford to pay that much for extra help. Therefore, if Congress institutes a subminimum wage, a new lower legal wage for teenagers, the teenage unemployment rate, which has been rising since 1960, will no longer increase.
(注释：priced out of the market：因价高而被挤出市场)
Which of the following statements, if true, would most weaken the argument above?
(A) Since 1960 the teenage unemployment rate has risen when the minimum wage has risen.
(B) Since 1960 the teenage unemployment rate has risen even when the minimum wage remained constant.
(C) Employers often hire extra help during holiday and warm weather seasons.
(D) The teenage unemployment rate rose more quickly in the 1970's than it did in the 1960's.
(E) The teenage unemployment rate has occasionally declined in the years since 1960.
先看完问题，发现是削弱题;再读原文，意思不难，很快提炼出其逻辑为如果国会制定更低的teenagers最低工资 ===》teenagers的失业率将不再上升，显然，正确选项首先要涉及最低工资和失业率之间的关系，而其他内容则为无关信息，可以排除。
显然A 和B都是相关的，而C在谈季节问题，D和E没有涉及失业率快慢的原因，都与原文逻辑无关，通通排除。
所以只需要仔细审视A和B
A： “最低工资上升的时候，失业率上升”，这与原文逻辑(更低工资将导致失业率不上升)形成了“反因反果”的关系，所以是加强。(比如：“不长跑的人不长寿”加强了“长跑的人长寿”)，这样A就被排除了。
所以答案只能是B
B的正面论证：
B：“最低工资不变的时候，失业率上升”说明失业率上升可能另有他因。这个论证的说服力不是很强，所以该题用排除法更有效。注意：削弱只是降低推理成立的可能性，而不需要推翻原文逻辑。
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