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二、GRE逻辑原文元素罗列和题型分类 |
逻辑题可按结构、内容、逻辑实质三个角度大致分类为四种题型：推理链题，归纳题，句子作用题（黑体题）和其他类。
逻辑链（argument）可以理解为前提推出结论的过程。GRE逻辑题中围绕推理链出的考题就称为推理链题，其又可以细分为以下六种考题：
（1）增加前提能够推导出结论可能性的考题——支持题。
（2）减少前提能够推出结论成立可能性的考题——削弱题。
（3）认为前提和结论间缺少某些补充性的必要因素——假设题。
（4）认为前提不能推出结论，结论由其他原因（他因）导致——解释题。
（5）测试通过前提推出结论的过程是否成立——评价题。
（6）用填空的方式考查之前五种题型——填空题。
考试中，最常见的题型就是推理链题，归纳题、句子作用题（黑体题）、其他类题基本在一次考试中各自出现1~2道。
何为前提，何为结论呢？
逻辑原文可以由六个元素组成：前提（premise）、结论（conclusion）、中间性结论（intermediate conclusion）、背景（background）、与结论方向相反的前提（counter-premise）、与结论方向相反的结论（counter-conclusion）。在做题时，不是所有元素都需要被概括进推理链，但前提和结论两个元素必须被概括进推理链。
1.前提（premise）的特征
（1）必须概括进推理链。
（2）用于支持结论（conclusion）。
（3）每一份逻辑原文都存在至少一个前提。
（4）可以被理解为得出结论（conclusion）的理由，故常接在表示原因的接续词（例如because, due to , for, the reason is that...等）之后。
（5）呈现方式可以是历史事件、统计数据、观点、事实等。
2.结论（conclusion）的特征
（1）不是所有逻辑文章都有结论。
（2）必须被概括进推理链。
（3）主要呈现方式是描述作者的主要观点，或预测，或是能解释文中现象的说法等。
（4）至少被一个前提（premise）所支持。
上述两个元素必须概括进推理链，需要注意的是前提可以不止一个，结论可以被多个理由（就是“前提”）所支持，而答案可以针对与理由相关的任何一个事件进行设置。
下面是四个不需要被概括进推理链的元素：
3.背景（background）
（1）不需要被概括进推理链。
（2）出现的目的是帮助读者更好地理解前提如何推出结论。
（3）呈现的方式可以是以客观事实、统计数据、某个术语的解释或定义等。
（4）并不是所有逻辑原文都存在背景。
4.中间性结论（intermediate conclusion）
（1）不需要被概括进推理链。
（2）是比较长的文章中的一个过渡性（先期性）结论，其逻辑方向和结论（conclusion）一致；结论就是中间性结论的一个进阶推理。
（3）中间性结论被某个前提所支持。
（4）中间性结论其本身又作为前提，支持最终的结论。
5.与结论方向相反的前提（counter-premise）
（1）不需要被概括进推理链。
（2）支持和结论态度相反的结论（counter-conclusion）。
（3）起到让考生混淆，增加找到正确推理链困难的作用。
6.与结论方向相反的结论（counter-conclusion）
（1）不需要被概括进推理链。
（2）态度方向和结论相反。
（3）被与结论方向相反的前提（counter-premise）所支持。
（4）和与结论方向相反的前提（counter-premise）一样，增加考生找到正确推理链的困难。
GRE考试中最常见的逻辑题题型如下：
In the United States, of the people who moved from one state to another when they retired, the percentage who retired to Florida has decreased by three percentage points over the past ten years. Since many local businesses in Florida cater to retirees, this decline is likely to have a noticeably negative economic effect on these businesses.
Which of the following, if true, most seriously weakens the argument?
A. Florida attracts more people who move from one state to another when they retire than does any other state.
B. The number of people who move out of Florida to accept employment in other states has increased over the past ten years.
C. There are far more local businesses in Florida that cater to tourists than there are local businesses that cater to retirees.
D. The total number of people who retired and moved to another state for their retirement has increased significantly over the past ten years.
E. The number of people who left Florida when they retired to live in another state was greater last year than it was ten years ago.
为原文，
为题目，再加上五个选项构成一道逻辑单选题。
注： 做逻辑题时，先读问题，知道问题问的方向和精准的考点之后再读原文，然后带着预测的答案方向再找选项，得出答案。
逻辑文章元素举例（1）：
An arrest made by a Midville police officer is provisional until the officer has taken the suspect to the police station and the watch commander has officially approved the arrest.Such approval is denied if the commander judges that the evidence on which the provisional arrest is based is insufficient. （background） A government efficiency expert has found that almost all provisional arrests meet standards for adequacy of evidence that watch commanders enforce. （counter-premise） The expert therefore recommends that the watch commander's approval should no longer be required since the officers' time spent obtaining approval is largely wasted. （counter-conclusion） This recommendation should be rejected as dangerous, （conclusion） however, since there is no assurance that the watch commanders' standards will continue to be observed once approval is no longer required. （premise）
解读： 句1、句2（An arrest made by a Midville ..... arrest is based is insufficient.）描述一个现象。现象本身没有直接支持某个结论，所以概括为“背景”。
句3（A government efficiency expert ... that watch commanders enforce）支持了一个态度和作者最终结论相反的结论，故概括为与结论方向相反的前提。
句4（The expert therefore recommends that .... obtaining approval is largely wasted.）中的“therefore recommends that..”说明本句是一个结论，但这个结论和作者最终的结论态度相反，因为之后有一个however，因此本句是与结论方向相反的结论。
句5的主句（This recommendation should be rejected as dangerous）有明确的态度评价，和句4呈相反关系，是作者最终的观点，故被认为是结论。
句5的原因状语从句（since there is no assurance that ... is no longer required）支持主句，作为结论的原因存在，被认为是前提。
逻辑文章元素的举例（2）：
Hunters alone are blamed for the decline in Greenrock National Forest's deer population over the past ten years. （background） Yet clearly, black bears have also played an important role in this decline. （conclusion） In the past ten years, the forest's protected black bear population has risen sharply, and examination of black bears found dead in the forest during the deer hunting season showed that a number of them had recently fed on deer. （premise）
解读： 句1（Hunters alone are blamed for ... past ten years.）描述了一个观点或现象，因此该句可概括为“背景”。
句2（black bears have also played an important role in this decline）中Yet提示本句和之前句子观点态度相反，句2之后是具体时间，表明后文是支持这句话的细节，所以句2被后文所支持，为结论。
句3（In the past ten years, the forest's protected ... had recently fed on deer.）属于句2的原因，即为前提。
7.考生答题的障碍：推理链的提取
解GRE逻辑题时，切记读文章的目的就是把推理链总结出来，读出推理链之前，不建议读选项。在总结的过程中，有以下几点需要特别强调：
* 推理链的总结步骤：先思考结论是哪句话，再想共有哪些事情推出了结论，这些事情全部是前提。
（1）多个前提的辨识。
一个结论可以被多个前提推出，那么如果前提有n个句子，就表示有n个前提吗？肯定不是这样。如果几个句子在说同一件事情，那就只有一个前提。多个句子在说不同的事情，这些事情都作为结论的理由或依据，这才是多个前提。（所有前提都需要被概括进推理链中）
（2）指代性词汇不进推理链。
Which of the following most logically completes the argument below?
Although the number of large artificial satellites orbiting the Earth is small compared to the number of small pieces of debris in orbit, the large satellites interfere more seriously with telescope observations because of the strong reflections they produce. Because many of those large satellites have ceased to function, the proposal recently has been made to eliminate interference from nonfunctioning satellites by exploding them in space. This proposal, however, is ill conceived, since ____.
此文的结论是“this proposal is ill conceived”，需要为这个结论找一个理由，此题相当于对一个计划进行削弱。如果考生把短文概括为“这个策略不行”，那么选项如果出现了与这个策略具体内容相关的信息，考生不会在第一时间反应过来其和原文推理链是相关的。因此如果把指代性词汇总结进推理链中，必须要把具体内容归纳进去。不能记成“这个策略不行”，而要记成“把坏的了卫星爆破的方案不行”。
（3）结论和中间性结论的判断。
中间性结论不需要被概括进推理链，而结论需要被概括进推理链。如果在原文中发现多个结论，哪个结论才是最终的，并且需要被总结进推理链呢？答案是“时间靠后”的那一个结论才是最终的结论。
例 The owner of a small publishing company plans to lease a new office space that has floor-to-ceiling windows and no internal walls, arguing that the new space will enhance worker productivity. The owner cites a recent study showing that workers exposed to natural light throughout the day tended to report, on average, a higher level of job satisfaction than did those who worked in office spaces that used fluorescent lighting. Thus, the owner concluded, exposure to natural light has a positive effect on workers' job satisfaction.
解读： 原文中出现两个结论，其一是“the new space will enhance worker productivity”，其二是最后一句话“the owner concluded, exposure to natural light has a positive effect on workers' job satisfaction”。从外在形式来看，第二个更像结论。但是在GRE考试中，如果考生仅凭形式而不思考意思来作判断的话，基本上总分不会超过680分。“增加创造力”和“提升满意程度”哪个“时间靠后”？“提升了满意程度，所以才会最终增加创造力”，所以第一个结论才是最终的结论。
从逻辑原文范围中可以概括总结出哪些信息——归纳题。
某个或某两个句子在逻辑原文中扮演的角色是什么，又称黑体题。
上述题型之外的题均称为其他类题型，出现概率很小。
面对如此多的题型，我们只需要记住一点，即“看清问题，回答问题”。在灵活的出题方式下，不能思维固化，在实际考试中碰到新变体题型，考生需做到随机应变，即不管出题形式如何改变，看准题目在问我们什么，答其所问即可。
例1 Yeasts capable of leavening bread are widespread, and in the many centuries during which the ancient Egyptians made only unleavened bread, such yeasts must frequently have been mixed into bread doughs accidentally. The Egyptians, however, did not discover leavened bread until about 3000 B.C. That discovery roughly coincided with the introduction of a wheat variety that was preferable to previous varieties because its edible kernel could be removed from the husk without first toasting the grain.
Which of the following, if true, provide the strongest evidence that the two developments were causally related?
解读： 题目问哪个选项提供证据表明文章中两个事件的发展是相关的。此题略像支持题，但支持题是增加前提和结论成立的概率，而此题所问的对象是文中的两个事件（two developments），和一般支持题有差异。
例2 Sonya: The government of Copeland is raising the cigarette tax. Copeland's cigarette prices will still be reasonably low, so cigarette consumption will probably not be affected much. Consequently, government revenue from the tax will increase.
Raoul: True, smoking is unlikely to decrease, because Copeland's cigarette prices will still not be high. They will, however, no longer be the lowest in the region, so we might begin to see substantial illegal sales of smuggled cigarettes in Copeland.
Raoul responds to Sonya's argument by doing which of the following?
解读： 题目问Raoul回复Sonya观点的方式（即Raoul如何评价Sonya的观点），不属于直接的推理链考题，考生需要读出Raoul削弱或支持Sonya的角度。
例3 In Patton City, days are categorized as having heavy rainfall（more than two inches）, moderate rainfall（more than one inch, but no more than two inches）, light rainfall（at least a trace, but no more than one inch）, or no rainfall. In 1990, there were fewer days with light rainfall than in 1910 and fewer with moderate rainfall, yet total rainfall for the year was 20 percent higher in 1990 than in 1910.
If the statements above are true, then it is also possible that in Patton City
解读： 此题并非归纳题，因为归纳题中答案描述的事件一定是逻辑原文中所描述事件的一个子集，或原文能推理总结出的一个事件。而此题问的是哪个选项可能对。何为“可能对”？只要不和原文内容冲突，任何事件都“可能对”。此题的答案范围完全可以脱离原文描述的事件范围，因此此题不能被认为是归纳题。