阅读了不少牛人关于GMAT逻辑题的心经，有的看不懂，不会运用；有的看懂了，但毕竟不是自己的，看过就忘了。今天试着开始用尽量简单的语言总结一下OGCR的做法及我的感受，希望自己有所收获，同时也希望大家看到的不吝赐教，挑出毛病来，共同进步。
一、Assumption题
确定为assumption题，读题干，看选项。先找有not的选项，如果有，看看是不是not+weaken，是的话基本上就是答案；不是的话，看剩下的选项有没有补充文章gap的，看这些选项的时候要思考是不是结论成立的必要条件，即问自己一定要这样结论才成立吗。
需要注意的细节（有待大家商讨以决定适用性）：
1) 如果5个选项都没有not，那么，有必要进一步认定这是个填补gap的题；排除选项的时候心里要默默的想文章中是不是缺少了这样的gap。如OG-21/63/76
例子：OG-21
When limitations were in effect on nuclear-arms testing, people tended to save more of their money, but when nuclear-arms testing increased, people tended to spend more of their money. The perceived threat of nuclear catastrophe, therefore, decreases the willingness of people to postpone consumption for the sake of saving money.
The argument above assumes that
A. the perceived threat of nuclear catastrophe has increased over the years.
B. most people supported the development of nuclear arms
C. people’s perception of the threat of nuclear catastrophe depends on the amount of nuclear-arms testing being done
D. the people who saved the most money when nuclear-arms testing was limited were the ones who supported such limitations（C）
E. there are more consumer goods available when nuclear-arms testing increases
OG解释：
On the basis of an observed correlation between arms testing and people’s tendency to save money, the argument concludes that there is a causal connection between a perception of threat and the tendency not to save. That connection cannot be made unless C, linking the perception of threat to the amount of testing being done, is assumed to be true. Therefore, C is the best answer.
2) 错误的选项包括无关选项、与原文不兼容选项等。无关选项的内容可能包罗万象，其种类作者没有详加分析，但有一种需要引起注意，即与原文兼容的（compatible）的选项，这类选项比较具有迷惑性，因为看不出明显的纰漏，这也是为什么要检验自己所选的答案是否必要的原因之一。
与原文不兼容选项举例：OG-167的E选项
Because no employee wants to be associated with bad news in the eyes of a superior, information about serious problems at lower levels is progressively softened and distorted as it goes up each step in the management hierarchy. The chief executive is, therefore, less well informed about problems at lower levels than are his or her subordinates at those levels.
The conclusion drawn above is based on the assumption that
(D) chief executives obtain information about problems at lower levels from no source other than their subordinates（D）
(E) some employees are more concerned about truth than about the way they are perceived by their superiors
OG解释：Choice E, if true, would tend to counteract the phenomenon the passage describes.
与原文兼容（compatible）选项举例：OG-63的D选项
Traditionally, decision-making by managers that is reasoned step-by-step has been considered preferable to intuitive decision-making. However, a recent study found that top managers used intuition significantly more than did most middle-or lower-level managers. This confirms the alternative view that intuition is actually more effective than careful, methodical reasoning.
The conclusion above is based on which of the following assumptions?
(D) Top managers use intuitive reasoning in making the majority of their decisions.（E）
(E) Top managers are more effective at decision-making than middle-or lower-level managers
OG 解释：The argument is consistent with managers at all levels using intuition in the minority of decisions made. Thus, choice D is inappropriate.
3) 无关排除法的应用要区别对待：对于有not的选项尽量不用无关排除，因为可能涉及到削弱；对于gap类型的选项则可以大胆使用，因为这类选项要弥补原文的推理缺陷，如果涉及到与原文结论无关的内容则当舍去。
以上是我的一点想法，欢迎NN们指正。明天继续。J
ethyl斑斑的大作啊~~当然要顶！
献花
不错
二、 Support题
做加强题好像没有那么多的技巧；但是，前辈们总结得很好，就是读完题后，要记住结论；并且是尽量记得详细一点，这样遇到任何一个选项你才能更好得判断是否有关；说记得详细一点，不是说要花半分钟一个词一个词得搞懂结论，而是花尽量少的时间记住尽量精准的结论，也许3、5秒，也许7、8秒，但不能再多了，因为我们还要看选项。
需要注意的细节：
1) 看选项的时候要带着结论看，用心看，只要结论记得精准，很多选项可以立即排除掉；比如下面的例子：
OG-32.
A recent spate of launching and operating mishaps with television satellites led to a corresponding surge in claims against companies underwriting satellite insurance. As a result, insurance premiums shot up, making satellites more expensive to launch and operate. This, in turn, has added to the pressure to squeeze more performance out of currently operating satellites.
Which of the following, if true, taken together with the information above, best supports the conclusion that the cost of television satellites will continue to increase?
A. Since the risk to insurers of satellites is spread over relatively few units, insurance premiums are necessarily very high.
B. When satellites reach orbit and then fail, the causes of failure are generally impossible to pinpoint with confidence.
C. The greater the performance demands placed on satellites, the more frequently those satellites break down.
D. Most satellites are produced in such small numbers that no economies of scale can be realized.（C）
E. Since many satellites are built by unwieldy international consortia, inefficiencies are inevitable.
读完题后马上找出结论，说成本会持续增加；那么看选项的时候心里就默默地念：持续增加，持续增加。
OG在解释ADE的时候说：A, D and E all describe factors relevant to costs, but there is no reason to think that the situation described in the passage will cause the costs resulting from these factors to increase. 意思就是，ADE跟成本都是相关的，但是仔细一看，Ａ说保险很贵，D说没有规模效益，E说效率成问题，都没能够突出成本会持续增加，所以全部无关。
那么，如果没有记住结论就看选项或者结论记得不精准就看选项会有什么后果呢？有时候结论可能记住大概就可以选出答案，但有时候记不准结论是要吃大亏的。比如下面的例题：
OG-82.
Excavation of the ancient city of
Which of the following, if true, most strongly supports the archaeologists’ hypothesis?
(B) No coins minted after A.D.365 were found in Kourion, but coins minted before that year were found in abundance.
(C) Most modern histories of
我做第一遍的时候选的是C，知道答案后却怎么也想不通为什么C不对。
OG对C的解释：Since choice C supports something already established, namely, that an earthquake occurred in A. D. 365, C is inappropriate.
其实，本题的结论是“破坏是由一起已知发生于公元365年的地震引起的”，这样的话，C说的就等于是大白话了。
2) Support题里面的错误选项通常包括无关选项、削弱选项。无关选项很多很多，比如结论的结果（OG-109的E选项），对原文非结论部分的支持（OG-89的D选项）等；削弱选项比较少见，一般也比较明显。
OG-109.
Recently a court ruled that current law allows companies to reject a job applicant if working in the job would entail a 90 percent chance that the applicant would suffer a heart attack. The presiding judge justified the ruling, saying that it protected both employees and employers.
The use of this court ruling as part of the law could not be effective in regulating employment practices if which of the following were true?
(B) No legally accepted methods exist for calculating the risk of a job applicant’s having a heart attack as a result of being employed in any particular occupation.
(E) The number of people applying for jobs at a company might decline if the company, by screening applicants for risk of heart attack, seemed to suggest that the job entailed high risk of heart attack.（B）
OG的解释：Choice E describes one indirect effect on the job market that might stem from the ruling.
OG- 89
In many corporations, employees are being replaced by automated equipment in order to save money. However, many workers who lose their jobs to automation will need government assistance to survive, and the same corporations that are laying people off will eventually pay for that assistance through increased taxes and unemployment insurance payments.
Which of the following, if true, most strengthens the author's argument?
(A)Many workers who have already lost their jobs to automation have been unable to find new jobs.
(D)Most of the new jobs created by automation pay less than the jobs eliminated by automation did. （A）
OG的解释：Since the author tacitly grants that, initially, automation will cut costs, the detail given in D provides us added support.
3) 其实根据我做OG的感觉，是否无关很重要的还是那点，就是跟原文的结论的关系紧不紧；有的选项跟结论简直是风马牛不相及，有的看似毫无关系但稍微进一步想一下就有关系；所以，剔除无关选项不能依靠哪个单词在文中出现过没有或者其在文中有没有同义词，而要靠其逻辑意思。
欢迎NN们指正。明天继续。J
三、 Flaw
之所以把flaw单独列出来，是因为参照了大牛lawyer的OG逻辑分类（可能大牛觉得削弱确实比较系统，要分得细一点）。
按照狒狒的说法，flaw类型的削弱有四个标志词：flaw, criticism, reasoning error和weakness；在OG上我们可以发现还有如下词表示flaw：absurdity, critique等。
做flaw题最可行的方法可能就是排除法了，当然牛人们一眼能看出flaw所在的话就直奔正确选项而去了。
需要注意的细节：
1) 不正确的选项包括无关、加强（OG-77的E）等
OG-77
A certain mayor has proposed a fee of five dollars per day on private vehicles entering the city, claiming that the fee will alleviate the city’s traffic congestion. The mayor reasons that, since the fee will exceed the cost of round-trip bus fare from many nearby points, many people will switch from using their cars to using the bus.
Which of the following statements, if true, provides the best evidence that the mayor’s reasoning is flawed?
(B) The cost of parking fees already makes it considerably more expensive for most people to take a private vehicle into the city than to take a bus.
(E) During the average workday, private vehicles owned and operated by people living within the city account for twenty percent of the city’s traffic congestion.（B）
OG的解释：
Choice E supports the mayor’s proposal by indicating that vehicles entering the city produce most of the city’s congestion.
2) 无关排除法可以大胆用（OG-16，44，47等）；之所以这样说是因为flaw是文章的推理缺陷，答案就要设置为与文章内容相关的。
OG-44.
Some people have questioned the judge’s objectivity in cases of sex discrimination against women. But the record shows that in sixty percent of such cases, the judge has decided in favor of the women. This record demonstrates that the judge has not discriminated against women in cases of sex discrimination against women.
The argument above is flawed in that it ignores the possibility that
A. a large number of the judge’s cases arose out of allegations of sex discrimination against women
B. many judges find it difficult to be objective in cases of sex discrimination against women
C. the judge is biased against women defendants or plaintiffs in cases that do not involve sex discrimination
D. the majority of the cases of sex discrimination against women that have reached the judge’s court have been appealed from a lower court（E）
E. the evidence shows that the women should have won in more than sixty percent of the judge’s cases involving sex discrimination against women
OG对无关选项的解释：
A and D have no bearing on the reasoning of the argument, because the origin of the cases is not at issue in the argument. B and C introduce considerations with no bearing on the reasoning of the argument. Because the argument concerns a particular judge, and cases of a particular type, B and C are inappropriate.
3) 无关选项包括完全无关、兼容（OG-26）
OG-26.
The average normal infant born in the
Which of the following indicates a flaw in the reasoning above?
C. It is possible for a normal child to weigh ten pounds at birth.
D. The phrase “below average” does not necessarily mean insufficient.（E）
E. Average weight gain is not the same as average weight.
OG对兼容选项的解释：
B and C are consistent with the claims in the passage, and neither identifies a flaw in the argument.
4) 对一些背景性质的内容进行削弱通常是无效的（OG-128）；之所以这里没有用前提性质，因为那样会引起歧义；在逻辑里前提是一个名词，是有定义的。至今我仍然不知道对前提的削弱是否无效；关于这点，还请牛人们多指教。
OG-128.
Reviewer:
The book Art's Decline argues that European painters today lack skills that were common among European painters of preceding centuries. In this the book must be right, since its analysis of 100 paintings, 50 old and 50 contemporary, demonstrates convincingly that none of the contemporary paintings are executed as skillfully as the older paintings.
Which of the following points to the most serious logical flaw in the reviewer's argument?
(A) The paintings chosen by the book's author for analysis could be those that most support the book's thesis.
(B) There could be criteria other than the technical skill of the artist by which to evaluate a painting.
(D) The particular methods currently used by European painters could require less artistic skill than do methods used by painters in other parts of the world.（A）
OG对BD选项的解释：
Choices B and D are both incorrect because a sharply defined focus is not a flaw in an argument; the reviewer makes clear that only artistic skill and only European painters are being considered.
注：这里有一个概念，即sharply defined focus，就是我所说的“背景性质的内容”；至于这个概念怎么解释，查了字典，觉得sharply在这里解释为“容易地、显然地”更恰当。
具体可参看Collins对sharp的解释：A sharp difference, image, or sound is very easy to see, hear, or distinguish.
e.g.: The women’s figure is sharply brought out by the intense light.
四、 Explanation
今天翻看OG，竟然发现所有的205道CR里面，竟然有25道解释题！
解释题分两种：解释结果和解释矛盾。根据狒狒的分类，解释结果的标志词有：explain, reason, account for, provide a rationale for等；解释矛盾的标志词有reconcile the discrepancy/paradox等。
这类题好像不是很难，方法呢，也比较简单。
正如做削弱题、加强题、假设题需要记住结论一样，做解释题需要记住需要解释的东西：结果或者矛盾。带着结果或者矛盾读选项，遇见无关的马上排除；遇到相关的选项，首先想能不能解释结果或者矛盾，如果能还要检验是否与原文矛盾。
需要注意的细节：
1) 错误的选项通常包括无关选项、相反解释选项（OG-148）等。
OG-148.
A discount retailer of basic household necessities employs thousands of people and pays most of them at the minimum wage rate. Yet following a federally mandated increase of the minimum wage rate that increased the retailer’s operating costs considerably, the retailer’s profits increased markedly.
Which of the following, if true, most helps to resolve the apparent paradox?
(A) Over half of the retailer’s operating costs consist of payroll expenditures; yet only a small percentage of those expenditures go to pay management salaries.
(B) The retailer’s customer base is made up primarily of people who earn, or who depend on the earnings of others who earn, the minimum wage.
(C) The retailer’s operating costs, other than wages, increased substantially after the increase in the minimum wage rate went into effect.
(D) When the increase in the minimum wage rate went into effect, the retailer also raised the age rate for employees who had been earning just above minimum wage.
(E) The majority of the retailer’s employees work as cashiers, and most cashiers are paid the minimum wage.
OG对ACDE项的解释：
Choices A and E are incorrect, since they suggest that the wages that rose as a result of the mandated increase constituted a significant proportion of the retailer’s expenditures, which if anything adds to the seeming paradox. Choices C and D also contribute to the paradox, since they indicate that along with increases in the minimum wage there were increases in the retailer’s operating costs; so choices C and D are also incorrect.
2) OG在解释错误选项的时候，经常说“Choice X does not explain why …”或者“Choice X explains why …, but not …”；可以看出来，大部分错误选项不是解释不了，就是解释了别的东西。从解释里面我们也可以得到启发，做题的时候，遇到错误选项不能只做到知其然，而且要做到知其所以然，知其然所以；即解释不了矛盾，可以解释什么。这样的话可以使我们的思路更接近出题者的思路。
3) 有一种错误选项需要指出，即与原文的推理相关但是解释的不是所需要解释的方面。举例说明：
OG-71.
Some communities in
Which of the following, if true, best reconciles the seeming discrepancy described above?
(A) The businesses specializing in the rental of children’s furniture buy their furniture from distributors outside of
(B) The few children who do reside in these communities all know each other and often make overnight visits to one another’s houses.
(C) Many residents of these communities who move frequently prefer renting their furniture to buying it outright.
(D) Many residents of these communities must provide for the needs of visiting grandchildren several weeks a year.
(E) Children’s furniture available for rental is of the same quality as that available for sale in the stores.
OG对AE的解释：
Similarly, choices A and E, though they provide information concerning the furniture that is rented in these communities, do not address the prior issue of why there should be such demand for children’s furniture.
这就对要求我们在读原文的时候，记牢所要解释的结果或者矛盾；否则，遇到相关选项就会手忙脚乱，不知所措，还得回到文中找相关信息。
欢迎NN们指正。明天继续。J
五、 Evaluation题
此类题的做法与加强和削弱题比较相似：读文章，记住结论，读选项。但是，这类题没有削弱题那么复杂，因为可以用无关排除法，而削弱题用无关的时候总是要小心翼翼；这类题也比加强题思路简单，因为加强题也不一定都能用无关排除法。
此类题的标志词比较少，大概有：evaluate、appraisal等。
与加强题和削弱题一样，对于评价题再强调记住精准的结论再强调都不过分，因为这首先关系到选项是否是相关的。
需要注意的细节：遇到有疑惑的选项的时候，进行双向检验，即相反的回答是否对结论分别造成支持或削弱。
下面通过一道OG例题来验证两点：1）记住精准的结论；2）双向检验。
OG-42.
In the aftermath of a worldwide stock-market crash, Country T claimed that the severity of the stock-market crash it experienced resulted from the accelerated process of denationalization many of its industries underwent shortly before the crash.
Which of the following, if it could be carried out, would be most useful in an evaluation of Country T’s assessment of the causes of the severity of its stock-market crash?
A. calculating the average loss experienced by individual traders in Country T during the crash
B. using economic theory to predict the most likely date of the next crash in Country T
C. comparing the total number of shares sold during the worst days of the crash in Country T to the total number of shares sold in Country T just prior to the crash
D. comparing the severity of the crash in Country T to the severity of the crash in countries otherwise economically similar to Country T that have not experienced recent denationalization（D）
E. comparing the long-term effects of the crash on the purchasing power of the currency of Country T to the immediate, more severe short-term effects of the crash on the purchasing power of the currency of Country T
读完题后马上得出结论：T国家认为股市震荡前发生的加速的私有化是股市震荡严重性的原因。
A，震荡中交易者的平均损失；这个不是结论关心的，因为首先要解决震荡的原因，而不是严重到什么程度。
B，下一次震荡的日子预测；无关
C，与A犯的是同样的错误。
D，与某国比较严重性，此国家在经济上与T相仿，只是没有最近没有经历私有化；将私有化作为比较对象，好像可以考虑；于是，进行验证，如果此国比T国的结果还要严重，说明不大可能是私有化导致的，如果此国没有T国的严重，那么私有化很可能就是严重性的原因；一个削弱，一个加强。正确。
E，一看购买力，好像还是在说严重不严重；无关
OG的解释：
The comparison suggested in D would be useful in evaluating Country T’s assessment of the cause of the severity of its stock market crash. If the severity of the crash is at least as great in the countries that are, except for recent nationalization, economically similar to Country T, Country T’s assessment is undermined. if the severity of the crash is not as great in these countries as in Country T, however, the assessment is supported. Thus, D is the best answer.
A, C and E are not good answers because each concerns only determining the severity of the crash in Country T, not assessing a hypothesis about the causes of the crash. The date of Country T’s next crash is not relevant to any hypothesis about what caused its latest crash to be so severe; thus B is inappropriate.
欢迎NN们指正。明天继续。J
斑斑大作，顶～
继续：
六、 Weaken题
削弱题在OG里面达到80道左右，可见其重要性；为什么ETS这么偏爱这种题型呢？我觉得这跟GMAT考试的宗旨是有一定联系的。进入商学院学习的学生需要有一定的辩驳思维，不能人云亦云、亦步亦趋，而又有自己的想法，遇到一个问题、一个观点都要惯性得进行思辨；这样在以后的生活中才能养成独立思考、解决问题的习惯。
知道问题是削弱题后开始读文章，大牛们经常说每读一句话都要思考在文章中的作用（比如mindfree总结的active reading），可是我却往往做不到，我能做的就是在读完题后努力找出结论，那么除了结论剩下的应该就是为结论服务的东东了（听着像废话，俺就是这么做的）。
然后就是挑选项了。没什么好说的，记住精准的结论找答案。
其实，我觉得削弱题和支持题的检验是相对而言比较难的，不像假设题可以代入题中看是不是必要条件；检验削弱题的时候，lawyer大虾这么说：问自己，是否该答案使作者再考虑他的观点或迫使作者做出反应或原文该前提能证明该结论吗。这个就比较难以把握，选项是自己选出来的，当然首先就认为它是削弱的，问自己有时候问不出来什么东西。我觉得这个时候，可以稍微花几秒钟时间，回到题中，重新把结论看一遍，看看自己第一遍看的时候有没有什么遗漏的或者不对的地方，然后再核实你认为正确的选项；当然，如果你很确认结论没记错，那么，就大胆选吧。
需要注意的细节：
1) 有几种比较特殊的类型。一种是结论为因果关系的：削弱方式大概包括他因、断裂（同因异果或者异因同果）、因果颠倒等。请看下面例题：
断裂：OG-9的D选项
OG-9.
A conservation group in the
Which of the following, if true, would cast the most serious doubt on the accuracy of the group’s contention?
D. Raccoons and owls are shy and active only at night; yet they are not generally feared and persecuted.（D）
OG对D的解释：
The group’s contention suggests that animals that are shy and active at night are feared and persecute for that reason. D establishes that raccoons and owls are shy and active at night, but that they are neither feared nor persecuted. Therefore, D is the best answer.
因果颠倒：OG-137的
OG-137.
A study of marital relationships in which one partner's sleeping and waking cycles differ from those of the other partner reveals that such couples share fewer activities with each other and have more violent arguments than do couples in a relationship in which both partners follow the same sleeping and waking patterns. Thus, mismatched sleeping and waking cycles can seriously jeopardize a marriage.
Which of the following, if true, most seriously weakens the argument above?
(D) People in unhappy marriages have been found to express hostility by adopting a different sleeping and waking cycle from that of their spouses.（D）
OG对D的解释：
The argument assumes that mismatched sleeping and waking cycles precede martial problems. Choice D weakens the argument by indicating that this assumption is false, and D is the best answer.
2) 结论为条件结论的。削弱方式就是当前提成立的时候，结论不成立；即充分条件被满足的时候，必要条件不能成立。尤其需要注意的是，对前提（即充分条件）的削弱是无效的。请看下面例题：
OG-2.
The average life expectancy for the
Which of the following, if true, would most seriously weaken the conclusion drawn in the passage?
C. The longevity ascribed to
OG对C的解释：
C is the best answer. This choice suggests that a significant proportion of
简单一点说就是，L夫妇如果在H生了孩子，那么也不一定活那么久；因为基因不同。
3) 错误选项包括无关选项、加强选项等。
OG-41.
Since the mayor’s publicity campaign for
Which of the following, if true, casts the most serious doubt on the conclusion drawn above?
A. Fares for all bus routes in
B. The mayor of
D. The number of buses entering the midtown area of
E. Surveys show that longtime bus riders are no more satisfied with the
OG对ADE（支持）及B（无关）的解释：
A eliminates decreased fares as a possible explanation for the increased ridership, so it supports rather than casts doubt on the conclusion.
D eliminates a possible explanation-that the increased ridership is a result of extra buses-and thus supports the conclusion rather than casts doubt on it.
E eliminates a possible explanation-that the increased ridership is a result of improved service-and thus supports the conclusion rather than casts doubt on it.
B. The mayor of
七、 Must Be True
这类题可能就是新东方FeiFei讲义上所说的归纳题吧。
标志词：conclusion、inferred、implied、supported、if above true, then it is also true等
关于support，如果提问形式如the statement above support which of the following，则表示归纳（must be true），如果提问形式如which of the following, if true, best support the conclusion, 则表示加强。
读题的时候FeiFei讲义上说：不要关心文章的推导过程，尽量减少思维，承认文章正确，只抓信息。对于此，我不敢苟同，因为实战中，用这种方法就可以搞定的题好像不是很多，至少我是这样认为的；如果四五行的单词读下来，不思考是怎样逻辑得联系在一起的，对做题的信心就是很大的打击。我更赞同lawyer的方法，简单点说就是：有结合点的就结合起来，有推理链的就将推理链提出来，什么都没有那就只好记住文章的内容。
看选项的时候最重要的还是排除法，因为归纳题要求答案的必须是文中的内容或者文中的内容能够推出来的；当然，有的题目很明显，比如结合点很多，结合的很紧密，或者充分必要性很强，这种情况下，正确答案是可以事先猜出来的。
需要注意的细节：
1) 错误选项包括无关选项、推理错误选项（OG-169的D）等。
OG-169.
Corporate officers and directors commonly buy and sell, for their own portfolios, stock in their own corporations. Generally, when the ratio of such inside sales to inside purchases falls below 2 to 1 for a given stock, a rise in stock prices is imminent. In recent days, while the price of MEGA Corporation stock has been falling, the corporation’s officers and directors have bought up to nine times as much of it as they have sold.
The facts above best support which of the following predictions?
(A) The imbalance between inside purchases and inside sales of MEGA stock will grow even further.
(B) Inside purchases of MEGA stock are about to cease abruptly.
(C) The price of MEGA stock will soon begin to go up.
(D) The price of MEGA stock will continue to drop, but less rapidly.（C）
(E) The majority of MEGA stock will soon be owned by MEGA’s own officers and directors.
OG对无关选项（ABE）及错误推理选项的解释：
Since the prediction in choice D runs counter to the stated generalization, choice D is not supported.
The passage does not suggest there will be an increase in the imbalance between such purchases and sales. Thus, choice A is not supported.
Similarly, the passage suggests neither that inside purchases are about to cease nor that the majority of MEGA stocks will soon be owned by MEGA officers and directors. Thus, neither choice B nor choice E is supported.
2) 推理错误选项可能是原文某命题的逆命题或者否命题或者将充分条件或必要条件加not（OG-25的B）等。
OG-25.
If there is an oil-supply disruption resulting in higher international oil prices, domestic oil prices in open-market countries such as the
Which of the following conclusions is best supported by the statement in the passage?
B. International oil-supply disruptions have little, if any, effect on the price of domestic oil as long as an open-market country has domestic supplies capable of meeting domestic demand.
C. The oil market in an open-market country is actually part of the international oil market, even if most of that country’s domestic oil is usually sold to consumers within its borders.（C）
OG对B的解释：
B and D are not supported, since each contradicts the claim that an international oil-supply disruption will lead to rising oil prices in an open-market nation.
3) 不能用数字推比例，反之亦然（OG-117的A）
OG-117. A company’s two divisions performed with remarkable consistency over the past three years: in each of those years, the pharmaceuticals division has accounted for roughly 20 percent of dollar sales and 40 percent of profits, and the chemicals division for the balance.
Which of the following can properly be inferred regarding the past three years from the statement above?
(A) Total dollar sales for each of the company’s divisions have remained roughly constant.
(C) The chemicals division has realized lower profits per dollar of sales than has the pharmaceuticals division.（C）
OG对A的解释：
The passage provides no information about total dollar sales, so choice A is incorrect,
4) 答案可能是原文某句话的重写或逆否命题或某几句话的重写（OG-11）
OG-11.
The fewer restrictions there are on the advertising of legal services, the more lawyers there are who advertise their services, and the lawyers who advertise a specific service usually charge less for that service than lawyers who do not advertise. Therefore, if the state removes any of its current restrictions, such as the one against advertisements that do not specify fee arrangements, overall consumer legal costs will be lower than if the state retains its current restrictions.
If the statements in the passage are true, which of the following must be true?
C. If the restriction against advertisements that do not specify fee arrangements is removed, more lawyers will advertise their services.（C）
OG对C的解释：
The supposition in c involves reducing by one the number of restrictions on the advertising of legal services. Any such reduction will, if the stated correlation exists, be accompanied by an increase in the number of lawyers advertising their services, as C predicts. Therefore, C is the best answer.
还要再说一点，经常发现有这样的选项，文中说某事物A（的价格、数量等）增长或者减少了，而某选项说组成A的各个部分（的价格、数量等）是怎么增长或者减少的；其实这样的选项一般情况下是无关的。如下面例题：
OG-15.
The cost of producing radios in Country Q is ten percent less than the cost of producing radios in Country Y. even after transportation fees and tariff charges are added, it is still cheaper for a company to import radios from Country Q to Country Y than to produce radios in Country Y.
The statements above, if true, best support which of the following assertions?
A. labor costs in Country Q are ten percent below those in Country Y.
C. the tariff on a radio imported from Country Q to Country Y is less than ten percent of the cost of
manufacturing the radio in Country Y.（C）
E. it takes ten percent less time to manufacture a radios in Country Q than it does in Country Y.
OG对AE的解释：
A and E give possible partial explanations for the cost difference, but neither is supported by the passage because the cost advantage in Q might be attributable to other factors.
之所以将最后一点单独列出，是因为这一点不仅在归纳题里面出现，而且在其他类型的题目里面也经常出现。
欢迎大家批评斧正！
八、 填空
填空题在OG里占到了7道，而且都比较简单，一般是不需要推导的，只需要记住文章说了什么东西然后找选项就可以。
另外呢，需要补出的部分所在的那句话很重要，有的问下面哪个是例子或者表现，有的问现象的原因等等，知道了这句话在讲什么，找选项的时候才能有的放矢。
看选项的时候排除无关选项仍然是非常重要的方法，因为正确的选项本身就是文章的一步分；但是，在举例题中，无关排除好像就无用武之地了。如下例题：
OG-38.
Which of the following best completes the passage below?
Established companies concentrate on defending what they already have. Consequently, they tend not to be innovative themselves and tend to underestimate the effects of the innovations of others. The clearest example of this defensive strategy is the fact that___.
A. ballpoint pens and soft-tip markers have eliminated the traditional market for fountain pens, clearing the way for the marketing of fountain pens as luxury or prestige items
B. a highly successful automobile was introduced by the same company that had earlier introduced a model that had been a dismal failure
C. a once-successful manufacturer of slide rules reacted to the introduction of electronic calculators by trying to make better slide rules
D. one of the first models of modern accounting machines, designed for use in the banking industry, was purchased by a public library as well as by banks（C）
E. the inventor of a commonly used anesthetic did not intend the product to be used by dentists, who currently account for almost the entire market for that drug.
问：最能体现防御策略的例子？
其实防御策略有两部分组成：不思创新；鄙视别人的创新。要同时满足这两个条件才能选。
A选项好像提到了创新（旧产品市场定位改变），但是没有体现对别人的创新的反应。错
B两点都没有体现。
C没有尝试新的产品，所以不思创新；对于新产品，采取将老产品优化的办法，所以是鄙视别人的创新。
DE两者都没有体现。
由本题我们可以看出来，即使在填空题里，大家做题的时候也需要尽量记住多并且准的原文信息。
九、 Boldface
这类题又叫句子作用题，OG中只有一道，却非常经典。
其实，如果一个论证过程只有一个论据和一个论点，那么很简单，不用出五个选项让大家选各个部分之间的关系；所以呢，出题机构会把论证过程写得详细一点，比如最常见的，首先说出一个观点，并且可能给出一两个论据来支持，然后说存在另一种情况或者观点，理所当然第二个结论及论据也出现了。不能再复杂了，否则大家都会受不了，选项也会庞大无比。
知道了这点就很简单了，有时候甚至不用读懂文章或者读完文章就可以知道ETS要干什么，因为文中通常会有转折词，如however, but等等，那么这个转折词可以将文章分成两部分，很有可能就是前面一种情况，后面一种情况。这样看boldface的关系就简单多了。
欢迎大家斧正！
对NN的景仰。。。简直不知道该说什么了。。。
好文，好文！敬佩，敬佩！请教NN，我怎么样才能把此文收藏起来啊？
楼上的：
用复制粘贴放到word里保存起来哈。
看了Ethyl 对逻辑题的感受，觉得很有帮助总结思路。这里有几点说一下：
1。Read the question first, before reading the material on which it is based.
这个是ETS自己说的，在OG 497页上 Test-taking strategies for critical reasoning。这是因为带着问题去看问题的时候更容易找到目标。而且一道GMAT逻辑可以问出不同的问题，我想这也可能是他们用来扩充Test Bank的一个手段吧，要不然太浪费资源了。这也是为什么很多机井出现同内容不同题目的缘故。另外GMAT的逻辑选择实际上是非常狭窄有限的，如果可以自由发挥的话其实正确答案可能远远不止一个，但问题是只有一个真确答案可以让你挑选，所以不能用散发思维来做题。最最有意思的一点，我觉得是ETS在教我们看 “诡辩” --- 相当一部分逻辑题根本就是不合情，但是很合理。看过一个很有名的古希腊诡辩（与GMAT无关）--- 一粒麦子掉下来没有声响，两粒麦子掉下来没有声响，三粒麦子掉下来没有声响，所以一袋麦子掉下来没有声响。我想进 B-School 以后征战商场口枪舌论讨价Ethyl还价的时候，这些诡辩技巧还是要的。 :-P
2. Be an active reader
对于active reading我的理解是边读边总结边思考，像古人说的读书要心到眼到，这是有意识的过程--你当知道你在读什么，要找什么。Ethyl 的方法像看的时候心里默默地念：持续增加 ~~~~ ~~~~，就是active reading的方法之一。
3。Support
OG-32 用的是以此类推的办法，1-->2-->3-->4-->5-->1-->2-->3... 这是个循环loop.
OG-82 用的是非正面证明
OG-89 应该是weaken题
4。Flaw (Fallacy)
这类题目有自说自话的感觉，结论又是自圆其说。但偶尔偶尔还是要用上点常识。
OG-44, 77 错在 ignore other possibilities
OG-26 玩文字游戏
OG-28 这个要有点统计上的概念，错在choose the inappropite samples
5。Must be true
这种题个人感觉是逻辑性最强的，诡辩题可能多在这里出现。
6。Last but not least
练习，练习，练习。
我也顶！
顶了明天看
顶啊！！！
LZ可是造福人类啊！
尤其是对我这样的懒人来说
Thanks~~
真牛
刚刚做完OG CR。还没总结。没形成自己的感觉呢。谢谢LZ的奉献。我要好好消化消化。
lz太厉害了呀！！！！Up
边练边找共鸣~
楼主的总结通俗易懂，适于实战，多谢了
好，顶哦。
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