GRE阅读题型解析——细节题（六）

　　逻辑题

　　GRE阅读中的逻辑题型和GMAT中的逻辑单题有很多相似之处。这类题型的数目不多，但是却包含了一些必要的逻辑推理知识，主要考察考生的逻辑推理能力。

　　逻辑题三大出题原则：

　　1、不需要专业的背景知识原则

　　阅读中的逻辑题都是基于其中的某一个段落，涉及的领域很广泛，像艺术、社会学、历史、教育、政治、体育、广告等。虽然涉及内容包罗万象，读懂文章、回答问题、无需任何学科、专业的特定知识，而应着重从逻辑推理的角度来思维。即使主题题是你未读到的，你的回答所需的一切信息均已包含在段落之中。

　　2、Which of the following 原则

　　逻辑题的大多数问题有which of the following, 要求你根据段落里所给信息及逻辑推理，从下面五个选项中选出一个选项，从而实现问题目的。有时，或许这个选项并不是专业知识背景下或常识中的最佳选项，但只要是五个选项中最能实现问题目的的选项就可以了。

　　3、If true 原则

　　If true在许多考题中出现，紧接在which of the following 之后，有时表达是if practicable, if accepted, if feasible, if correct等。这使得选项在即使违反常识或专业知识的情况下，我们也不能质疑其正确性。

　　阅读中的逻辑题型分为两种：

　　1、支持

　　这类考题的特征在段落中给出一个推理或论证，但或者由于前提的条件不够充分，不足以推出其结论;或者由于论证的论据不够全面，不足以得出其结论，因此需用某一选项去补充其前提或论据，使推理或论证成立的可能性增大。但由于答案不需要充分性，所以只要某一选项放在段落推理的论据或结论之间，对段落推理成立或结论有支持作用，使段落推理成立、结论正确的可能性增大，那么这个选项就是支持的正确答案。

　　2、反对

　　反对题型的解题思路与支持题型的解题思路基本一样，只不过是其答案对段落推理的作用刚好相反。

　　下面我们举一些例子来说明：　　

　　It has long been known that during an El Nino, two conditions exist: unusually warm water extends along the eastern Pacific, principally along the coasts of Ecuador and Peru, and winds blow from the west into the warmer air rising over the warm water in the east. These winds tend to create a feedback mechanism by driving the warmer surface water into a pile that blocks the normal upwelling of deeper, cold water in the east and further warms the eastern water, thus strengthening the wind still more. The contribution of the model is to show that the winds of an El Nino, which raise sea level in the east, simultaneously send a signal to the west lowering sea level. According to the model, that signal is generated as a negative Rossby wave, a wave of depressed, or negative, sea level, that moves westward parallel to the equator at 25 to 85 kilometers per day. Taking months to traverse the Pacific, Rossby waves march to the western boundary of the Pacific basin, which is modeled as a smooth wall but in reality consists of quite irregular island chains, such as the Philippines and Indonesia.　　

　　Which of the following, if true, would most seriously undermine the validity of the model of El Nino that is presented in the passage?

　　 During some years El Nino extends significantly farther along the coasts of Ecuador and Peru than during other years.

　　 During periods of unusually cool temperatures along the eastern Pacific, an El Nino is much colder than normal.

　　 The normal upwelling of cold water in the eastern Pacific depends much more on the local characteristics of the ocean than on atmospheric conditions.

　　 The variations in the time it takes Rossby waves to cross the Pacific depend on the power of the winds that the waves encounter.

　　 The western boundary of the Pacific basin is so irregular that it impedes most coastal Kelvin waves from heading eastward.

　　分析：

　　先弄清题目的意思，是属于哪种题型。题目的意思是一下哪种说法将最大程度削弱文中所谈预测厄尔尼诺的模型的有效性?，通过题目的意思，我们知道这道题属于weaken题型。之所以会问这样的weaken的问题，那么，文中一定有相应的叙述。

　　文中的定位是：Taking months to traverse the Pacific, Rossby waves march to the western boundary of the Pacific basin, which is modeled as a smooth wall but in reality consists of quite irregular island chains, such as the Philippines and Indonesia.即说西海岸在模型中被描绘为光滑的墙，但实际上包含很多不规则的岛屿，如菲律宾和印尼这些国家。此处做了一个假设：该模型的设想和真实的地理环境的差异是不影响模型有效预测厄尔尼诺现象的。想要weaken原结论，就应该将漏洞暴露出来，根据选项，如果岛屿过多，阻止了K波返回，则不能形成反馈机制，也就不能形成EI Nino现象。这个前提也正是E选项所表达的，所以正确选项是E.

　　小结：

　　逻辑题不管是哪种类型，本质上都是一样的。只要在题目中有这样的题型，原文中肯定会有相应的内容，即叙述了一个现象，然后得到了一个结论。在解答这类题时的关键是，寻找出现象和结论之间联系的漏洞。这种思路是一切推理题本质上的出发点。