换句话说,参加新GMAT考试的考生,除了需要加强综合推理能力的训练,仍可以按照以往GMAT考试的方式进行其它部分的备考,当然也包括逻辑部分。下面,我给大家简要介绍一下GMAT逻辑部分在备考过程中需要注意的一些知识点和问题。
一、 GMAT逻辑考试形式
GMAT逻辑题是由一篇100字左右或更少的逻辑推理短文、问题题干及5个选项组成,并作为单独一类题型出现在Verbal Reasoning部分中,一般来说此部分的前10道题中都会出现一定数量的逻辑题,而逻辑题在整个Verbal部分的41道题中占11题左右。
GMAT逻辑题大致可分为演绎题(包括假设题、加强题、削弱题、评价题)、归纳题、解释题、逻辑方法题四大类。演绎题占到整场考试逻辑题总量接近一半,而其中又以削弱题的出现频率较高。一般来说题型分布是比较均衡的。
二、GMAT逻辑备考:中国考生困难在哪里?
1. 阅读
如果逻辑一直做不好,首先要评价一下自己是不是文章没有真正读懂,因为往往遗漏掉文章中的一些关键的细节信息会造成对推理无法正确把握。而且,大部分的逻辑文章都会用较多的背景信息以及长难句来增加理解上的难度,这样就造成了阅读能力有限的同学在坐起逻辑题来比较困难。因此,若因为阅读而导致逻辑受影响,首先需要加强的就是阅读训练。
2. 提炼
不论是考场上还是今后如战场的商场上,提炼关键信息都是至关重要的,因为这可以为你节省下大量的时间从而更高效地应对工作生活中爆炸的信息量。中国学生往往不习惯用最简短的语言复述别人讲的话,这样在逻辑题的解题上就吃亏了——因为逻辑文章里的“废话”其实可以很多,真正推理的主干也许就几个单词。一个人,如果用和别人一样容量的大脑去分析比别人少10倍信息量的精华推理,他的效率肯定是更高的。
3. 发散
因为教育模式和文化习惯的影响,中国考生的思维方式与GMAT逻辑所考查的思维方式可以说是大相径庭——前者是发散型的,后者是直线型的。中国考生往往想得太多,总认为出题人故意设计了需要拐很多弯才能成立的推理,但GMAT考试作为一个标准化测试,尤其是在逻辑推理的考查中,特别强调客观性——试想,若允许任何一位考生以多步跳跃的方式得到正确答案,那么将永远没有标准答案可言。因此,考生在备考一段时间后会发现,头脑变简单了,同时一些原本看起来迷惑不已的选项再也不必浪费时间纠结了。
下面我们用一道题目来讲解如何按照正确的解题步骤,克服上述困难,把题目做对。
The skulls and pelvic bones of some species of dinosaur share characteristics with the skulls and pelvic bones of all modern birds. Even though not all dinosaurs have these characteristics, there are scientists who claim that all animals that do have these characteristics are dinosaurs.
If the statements above and the claim of the scientists are true, which of the following must also be true?
A. Birds share more characteristics with dinosaurs than they do with other animal.
B. Some ancient dinosaurs were indistinguishable from modern birds.
C. All animals whose skulls share the characteristics of those of modern birds also have pelvic bones that are similar to those of modern birds.
D. Modern birds are dinosaurs.
E. All dinosaurs are birds.
当拿到一道逻辑题时,首先要做的事情便是看问题题干,这样才能更好地把握文章推理的精华主干。这是一道称为Must Be True型的归纳题,也就是选择一个根据原文必然正确的选项,我们必须通读原文。
说到读文章,如果掌握了阅读技巧的考生,读完原文首句,脑子里留下的就是“恐龙=现代鸟”,这里最重要的是事物间的关系。二句所强调的是后半句,即“有此特征的都是恐龙”。因此两者结合,即现代鸟都是恐龙,答案选择D.
A中出现了将鸟类与其它动物的一个比较,虽然从常识上说可能的确如此,而且很多同学脑子里会想:“鸟类是从恐龙进化而来的,那么它们与恐龙共有的特征当然比其它动物多得多。”这就是典型的发散,实际上这个比较的结论根本无法从原文得出;B是很有可能成立的选项,但却非一定成立,因此也排除;C选项错误地将文中并列的头骨和骨盆骨分离开来进行推理,显然错误;E选项则是完全说反了。
三、GMAT逻辑备考:套路和直觉
在最开始准备GMAT逻辑时,大部分考生都处于一种茫然、凭感觉、不稳定的答题状态中,这是正常现象——实际上,最终考生达到的理想状态,其实也是一种“直觉”,因为在把握了出题人的答案设计套路,并且经过了足量的练习,将解题技巧烂熟于胸之后,你往往看到正确选项便有一种被提示的兴奋感。
这就是为什么要对逻辑题的题型和套路进行分类的原因。下面我们用两道削弱题让大家体会一下什么叫GMAT逻辑题的套路。
The ice on the front windshield of the car had formed when moisture condensed during the night. The ice melted quickly after the car was warmed up the next morning because the defrosting vent, which blows only on the front windshield, was turned on full force.
Which of the following, if true, most seriously jeopardizes the validity of the explanation for the speed with which the ice melted?
A. The side windows had no ice condensation on them.
B. Even though no attempt was made to defrost the back window, the ice there melted at the same rate as did the ice on the front windshield.
C. The speed at which ice on a window melts increases as the temperature of the air blown on the window increases.
D. The warm air from the defrosting vent for the front windshield cools rapidly as it dissipates throughout the rest of the car.
E. The defrosting vent operates efficiently even when the heater, which blows warm air toward the feet or faces of the driver and passengers, is on.
这道题的推理精华是“冰融化得快是因为空调开最大”,按照我们解题的套路是先判断它的假设,再进行反对。对于这一类典型的“现象解释型“文章,其假设的套路是“空调开最大是导致冰融化得快的唯一原因”,而我们要对此进行反对,当然是“空调开最大不是导致冰融化得快的唯一原因”或“还有其他原因导致冰融化得快”,我们可以把以上这句削弱的套路称为特征甲。当大家读完这道题的选项后会发现,没有与特征甲直接吻合的选项,但你会发现B选项其实表达的意思是一样的。
我们再来体会一下这一道题:
A conservation group in the United States is trying to change the long-standing image of bats as frightening creatures. The group contends that bats are feared and persecuted solely because they are shy animals that are active only at night.
Which of the following, if true, would cast the most serious doubt on the accuracy of the group’s contention?
A. Bats are steadily losing natural roosting places such as caves and hollow trees and are thus turning to more developed areas for roosting.
B. Bats are the chief consumers of nocturnal insects and thus can help make their hunting territory more pleasant for humans.
C. Bats are regarded as frightening creatures not only in the United States but also in Europe, Africa, and South America.
D. Raccoons and owls are shy and active only at night; yet they are not generally feared and persecuted.
E. People know more about the behavior of other greatly feared animal species, such as lions, alligators, and snakes, than they do about the behavior of bats.
同样是一篇典型的“现象解释型”文章,其推理精华是“人们害怕并迫害蝙蝠仅仅因为它们是夜间活动的害羞动物”,而其假设的套路仍是“夜间活动的害羞动物是导致蝙蝠被人害怕并迫害的唯一原因”。现在我们做的是削弱,看看能不能找到“夜间活动的害羞动物不是导致蝙蝠被人害怕并迫害的唯一原因”这个选项呢?乍一看上去没有完全吻合的,但仔细阅读和思考各个选项后你会发现,D选项讲的是不是也是一个道理呢?
通过这两道题,我们能够体会到,出题人在设计题目时,采用的套路是大同小异的,也可以叫做“换汤不换药”。为什么有些题目难,很多考生做不出来、或者做不对呢?一个重要的因素还是在阅读、提炼和发散这三点上。再者,由于训练太少,很多套路的感觉还没有能够在你脑中形成根深蒂固的条件反射,会造成很多模棱两可的情形,这就是所谓的瓶颈,是需要不断的总结和训练才能够突破的。
四、 GMAT逻辑备考:永远也做不完的总结
很多考生都会问这样的问题:每天做多少题才够?实际上这是一个高度个人化的问题,答案是:取决于你是否能够消化掉之前所做的题目,否则再做新题就是纯粹的浪费。我们说,对于错题、甚至对题的总结,把它细致地做上10题,也比根本不去复习地做上100题在提高自身水平上的作用要强得多;实际上,每次看一遍之前做的题目,仔细体会一下,都会有新的发现,这就是逻辑题吸引人的地方;久而久之,你会发现,正确答案其实长得都像孪生兄弟般差不多,而错误答案却看上去是那么地让你熟悉得千疮百孔!正所谓幸福的人大致相同,不幸的人各有各的不幸。
最后,我们用一道题目来作结。大家可以先自己做一做,再好好体会一下为什么能选对,或为什么会选错。
Veteran screenwriters, aiming at creating a 120-page screenplay for a film, usually turn in a 135-page first draft. As one screenwriter put it, “That gives those in charge of the movie a chance to be creative when they get the script: at the very least, they can cut 15 pages. ”
The screenwriter’s statement cited above conveys which of the following propositions?
A. Screenwriters for a film are generally not involved in any aspects of filmmaking besides providing the script
B. Seasoned screenwriters are resigned to, and make allowance for, draft scripts being altered by those evaluating them
C. Truly creative screen writers are too temperamental to adhere to page limits set for their work
D. It takes a special kind of creativity to recognize what is best left out of a film script
E. Even experienced screenwriters cannot be expected to write scripts of consistently high quality throughout.
这道题的干扰选项较多,甚至有的同学认为每个选项都有道理!其实不然,作为归纳题,它是有固定的解题套路的。选A,说明原文没看懂;选B,说明抓住了原文末句改写而且也不怕改得直接;选C说明大概看懂了但没抓住点子;选D说明基本看懂了但没掌握技巧;选E说明该收一收了,发散了!“故意多写15页”是否等于“写出了质量不高的作品”?
总之,希望各位考生能够从自己最弱的点出发,将自己身上的“顽疾”克服,要相信,GMAT逻辑通过套路的总结和认真的演。
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