下面是写在前面的几条总纲：
1. 当一个选项不是很看得懂其与argument之间潜在逻辑关系时，或突然开始扯new information时，很容易被视作无关，而事实上却是他因。
2. 本总结说到了causality，numbers and percentages两种击破吧。应该还有一种做无关比较点，比如原文纵比，选项横比就错。
3. The GMAT always makes you pay if you gloss over any section of a stimulus.
4. 出题人在设置错误选项时，也出了同样的力，花了同样的心思。所以应该同样地重视错误选项。摸透出题人的心理。
5. 如果遇到的是Causality、numbers and percentages、structure and wholeness，在做练习的时候，每题多花几秒钟时间在题号标出，这三种题都是可以非常迅速地预测的(当然其他类题型也有可以预测的)。
6. 逻辑还是要靠排除法比较好(比如用out of scope, shell game, opposite)，正向做法只是confirm用的。
7. 结论有比较，正确选项通常也会有比较
8. 逻辑遇上长问题了一定要用contender标注法(事先在草稿纸上弄好表格)。
9. 所有的练习，都是为了强化(验证)或完善(微调)你的思路而存在。
10.时间状语、地点状语、频率状语总是很重要，非常重要，因为起限定作用;这些词如果出现在结论中，基本会有选项涉及到这些状语。
11.做一个题的时候，如果感觉到有别的出题方式，那就该随心想想如本来是weaken题，那出成strengthen的话，哪个攻击点可以被补上。
12. inference题和assumption题中，有绝对化词语的一般都不对，比如only。因为这两类题目都是要找肯定必须正确的东西：前者是推论，后者是必要条件。
13. 逻辑中，最重要的是锻炼提取关键词的能力，关键词，一个意群不超过3个词。包括在看不懂句子时，如果可以识别关键词，那么看下面哪个选项没有提及有关那个关键词的概念，就是无关选项。
例：Many geologists theorize that the trail of volcanic craters and cinder cones along the Snake River plain of southern Idaho was produced as the North American continent slid westward over a stationary “plume”, a vertical channel through which molten rock rose intermittently from the Earth’s core to burst through its curst.
Which of the following, if true, tends to support the geologists’ theory of how the trail was produced?
(A) The largest craters and cinder cones are on the eastern margin of the trail.
(B) The most violent volcanic activity apparently occurred at the western margin of the trail.
(C) The craters and cinder cones are evenly spaced throughout the extent of the trail.
(D) The newest craters and cinder cones are on the eastern margin of the trail.
(E) The craters and cinder cones on the western margin of the trail generally took longer to form than did those on the eastern margin.
即便看不懂题目，但也可以感觉到westward是关键词，那么选项中没有提到方向性词语的就是错误选项。
C完全和题目没有任何关系，没有提到任何方向的问题。A中largest无关，B中most violent无关，E中原文没有比较，那么E中出现了比较也就是错的了。 à 如果是因为生词多看不懂题目，千万不要一直想看懂，而应该瞬间提取关键词，看不懂的字用首字母代替即可，关键词从来都不会是难词。关键词，一个意群不超过3个词。
引自Lawyer11的一段话： --- 我感觉也还是关于提取关键字，然后建立各关键字之间联系的意思。
为了实现题目方向的要求，题目中提到的各元素关系应该有什么变化，或者新加入一个元素和题目中的元素有什么样的关系，最后就是在选项中找到符合这种关系的选项，与你心中目标最match的那个选项就是正确选项：
举个例子，就是GWD访谈里谈到的“冬天的积雪会将树枝压断，打到车上使得汽车受损，但是由于树枝打到车上使车受损的量，秋天比冬天多很多。”问解释?分析LOR：A与B的比较，A比B在甲属性上更如何如何的多/高，然而A比B在乙属性上却如何如何的少/低。问解释，必然是因为B比A在某属性上更如何如何导致上述看似反向的关系。GWD提供的此题的一个错误选项是“汽车车主知道冬天的积雪会将树枝压断打到车上，所以在冬天的时候他们根本没有把车放到树下。”分析此选项，关系是“A在某属性上如何如何”，根本没有A与B的比较，因此不可能是正确答案。还有一个选项是“秋天的风比冬天的风更大，它会把更多的树枝刮断。”分析此选项，关系是“B比A在某某属性上如何如何”，就是分析出来的解题方向，因此正确;如果不放心，还可以再理解一遍选项，发现的确是构成了解释。
举例2，还是GWD访谈中的例子“在动物园工作的人由于接触动物，30%的人得了过敏症。那么，在总人口中，接触动物的人群中超过30%的人得了过敏症。问题是下面哪个选项支持原文所说?”分析LOR：A由于B导致C属性，所以D由于B也有C属性。要支持原文结论，必然是将A与D之间建立正相关的关系。看选项“在动物园工作的人经常换工作。”是不是将A与D建立了某种关系?想象有一条线把“动物园工作的人”和“经常换工作”和“总人口”三者串了起来。虽然这个选项看起来无法理解，但你不需要理解这种非充分性加强到底是怎么加强的，你只要知道的确在两个元素间建立了某种关系，这就ok了。
再说一句，实际思考的时候，你不必自己在头脑中定义说某某事物是A，某某属性是B等等;你只要在考虑元素关系的时候在头脑中想象，题目中的元素之间有一条线将这个东东和那个东东连起来，或者反之，两个东东之间有个大叉号。不要为了使用这个方法而使用把ABCD甲乙丙丁等符号加到思考中，我提到这些只是为了方便解释。
总结一下，我的CR方法就是，找元素及元素间关系，然后按照题目方向在某些元素之间建立关系或者破坏某些元素之间的关系。
PS：除了使用这种方法，我还根据典型无关选项的特点来排除选项(典型无关见上面综合经验区的薰衣紫草的帖子)，或者什么方法也不用，就是CR的典型出题方式，想都不用想就是那种答案;总之不要在一棵树上吊死，哪个方法能解决这题，这题就用哪个方法。
目录
Chapter 1. 4
Chapter 2. 4
Chapter 3: 5
Chapter 4: Must Be True Questions. 7
Chapter 5: Main Point Questions. 10
Chapter 6: Weaken Questions. 11
Chapter 7: Cause and Effect Reasoning. 14
Chapter 8: Strengthen, and Assumption Questions. 17
Chapter Nine: Explain Questions è 他因型 support题... 23
Chapter 10: Method of Reasoning and Flaw in the Reasoning Questions. 27
Chapter 11: Parallel Reasoning Questions. 30
Chapter 12: Numbers and Percentages. 34
Chapter 13: Evaluate the Argument Questions. 35
Hard Questions. 36
Chapter 1
1. 700-800:
Quantitative: complete every question, average of just under 2 minutes per question.
Verbal : complete every question, average of 1 minute, 45 second per question.
*: 容易题不要超过45秒，难题不要超过90秒。
*: 学会边看时间边做也不会分心。
2. Don’t read the question stem before reading the stimulus.
Chapter 2
1. Premise: support and explain the conclusion
Additional premise: support the conclusion but is sometimes non-essential to the conclusion.
Counter-premise: also called adversatives, bring up points of opposition or comparison
2. Sub-conclusion: also known as subsidiary conclusion, a statement can be both a conclusion for one argument and a premise for another. In this sense, a complex argument can appear somewhat like a ladder, where each level or “rung” is used to build the next level.
*: On the GMAT, there are typically three or four levels at most.
3. While at the opening of a sentence could also lead a comparative clause:
While many of the arguments that appear on the GMAT are simple arguments, there are also a fair number of complex arguments.
4. A commonly used construction: one of the most frequently used constructions is to raise a viewpoint at the beginning of the stimulus and then disagree with it immediately thereafter.
Indicators such as:
“Some people propose”, “Many people believe”, “Some critics claim”
The structure of this opening sentence is remarkably consistent in form, and adheres to the following formula:
A number (some, many, etc.) of people (critics, students, teachers, legislators, vegetarians, psychologists etc.) believe (claim, propose, argue, etc.) that…
Of course, there are exceptions with slight alteration.
“Although some people claim… (Starts with “although”)”
“It has been claimed that… (Drops the number and people)”
5. Inference: In logic, inference can be defined as something that must be true.
Remember,” infer” means “must be true.”
Assumption: an assumption is simply the same as an unstated premise—what must be true in order for the argument to be true.
Their difference: an inference is what follows from an argument (in other words, a conclusion), whereas an assumption is what taken for granted while making an argument. In one sense, an assumption occurs “before” the argument, that is, while the argument is being made. An inference is made “after” the argument is complete, and follows from the argument.
All authors make assumptions when creating their arguments, and all arguments have inferences that can be derived from the argument.
6. Should-be-noted modifiers:
Quantity Indicators: all, every, most, many, some, several, few, sole, only, not all, none.
Probability Indicators: must, will, always, not always, probably, likely, would, not necessarily, could, rarely, never.
*: There are numerous examples of incorrect answer choices that attempted to capitalize on the meaning of single word in the stimulus and thus you must commit yourself to carefully examining every word on the test.
7. There are always definite, identifiable reasons that can be used to eliminate incorrect answer choices.
Chapter 3:
1. The ten critical reasoning question types:
(1) Must Be true/ Most Supported -- inference
(2) Main point (a variant of Must Be True)
(3) Method of Reasoning (including Boldface question)
(4) Flaw in the Reasoning
(5) Parallel Reasoning
==============above are included in the first family (Prove family) ===========
(6) Assumption
(7) Strengthen/ Support
(8) Explain (Resolve the Paradox, Discrepancy)
==============above three are included in the second family (Help family) ========
(9) Weaken
==============weaken belongs to the third family (Hurt family)=========
(10) Evaluation = strengthen + weaken.
2. When a stimulus without a conclusion appears on the GMAT, only two types of questions can be posed to you: Must Be True or Resolve the Paradox (Explain).
Resolve the Paradox questions are easy to spot because they contain a paradox or discrepancy.
Thus, if you encounter a stimulus without a conclusion and without a paradox, you are most likely to see a Must Be True question stem.
3. The following rules apply to the First Question Family:
(1) You must accept the stimulus information – even if it contains an error of reasoning – and use it to prove that one of the answer choices must be true.
(2) Any information in an answer choice that does not appear either directly in the stimulus or as a combination of items in the stimulus will be incorrect.
4. The following rules apply to the Second and Third Question Family:
(1) The information in the stimulus is suspect (errors of reasoning present, or leaps in logic). There are often reasoning errors present, and depending on the question, you will help shore up the argument in some way.
(2) The answer choices are accepted as given, even if they include “new” information. Your task is to determine which answer choice best meets the question posed in the stem.
5. “Most” in Question Stems: even though “most“will appear in many stems, you can rest assured that only one answer choice will meet the criteria. The test makers insert “most” into question stems just want to eliminate a predicament/quandary and maintain test integrity.
“Except” and “Least” in Question Stems: when “least” has a similar effect to “except” when it appears in a question stem you should treat it exactly the same as “except”. (Note: this advice holds true only when this word appears in the question stem!)
6. Ten Primary Objectives:
#1: Determine whether the stimulus contains an argument or if it is only a set of factual statements.
#2: If the stimulus contains an argument, identify the conclusion of the argument. If the stimulus contains a fact set, examine each fact.
#3: If the stimulus contains an argument, determine if the argument is strong or weak.
#4: Read closely and know precisely what the author said. Don’t generalize! (有时候在读选项时要回原文定位关键词，包括限定词、修饰词、以及范围词等等—> Modifier Words Revisited.
#5: Carefully read and identify the question stem.
#6: Prephrase: after reading the question stem, take a moment to mentally formulate your answer to the question stem.
#7: Always read each of the five answer choices. (Parallel Reasoning Question could be an exception.)
#8: Separate the answer choices into Contenders and Losers. After completing this process, review the contenders and decide which answer is the correct one. This process saves time, to nearly 20 second!
#9: If all five answer choices appear to be Losers, return to the stimulus and re-evaluate the argument. (插入到#8中)
Chapter 4: Must Be True Questions: -- 这一章的重要性真的不仅仅限于CR中有这样的题型，在RC里面的Inference题其实就是MUST BE TRUE题。所以掌握正确答案特征(paraphrase + combination)、错误答案特征()非常非常重要。
1. Must Be true题要学会做笔记，以尽量做到减少回到题干的次数，每次浪费五六秒加起来就十几秒了。每读原文中的一个事，就把这事在笔记上记下来。记笔记的方法如下：
假如有a,b,c三件事，则这三件事有四个交集：a + b, a + c, b + c, a + b + c，(因为答案不会就一件事情做一个inference，所以一件事情的不用考虑)。之后对着选项看，看选项能不能用总结出这四个交集之一的表达。
*：当然有时候
2. The correct answer choice can be:
(1) a paraphrase of part of the stimulus
(2) a logical consequence of one or more parts of the stimulus.
3. 看一道练习体会”read precisely”与”inference should match the premises/stimulus”的意思：
Flavonoids are a common component of almost all plants, but a specific variety of flavonoid in apples has been found to be an antioxidant. Antioxidants are known to be a factor in the prevention of heart of disease.
Which one of the following can be properly inferred from the passage?
(A) A diet composed largely of fruits and vegetables will help to prevent heart disease.
(B) Flavonoids are essential to preventing heart disease.
(C) Eating at least one apple each day will prevent heart disease.
(D) At least one type of flavonoid helps to prevent heart disease.
(E) A diet deficient in antioxidants is a common cause of heart disease.
分析：
(A) 选项中的will与stimulus中的almost不匹配，fruits and vegetables与a specific variety不匹配(out of scope)。一来就标记为Loser。
(B) essential与a factor不匹配。一来就标记为Loser。
(C) Will与a factor in the prevention不匹配。一来就标记为Loser。
(D)正确。The language of this answer choice – “helps to prevent” – matches the stimulus language – “a factor in the prevention”.
(E)一来就标记为Loser。 “Cause of heart disease” is irrelevant to the stimulus. à the stimulus makes no mention of the cause of heart. 芯芯锡
(1)本题也没有任何选项被标记为Contender，所以是简单题。
(2)通过分析可以看出来。Almost和a factor是关键词(适用其他题目)，同时与a factor匹配的help可能在其他题目里面成为关键词。
(3)题干中有almost all, a factor in the prevention这种relatively broad的词，则答案中不会出现很绝对的说法。
4. 从上例可以看出来modifier words revisit的重要性。这一点在Must Be True题型里特别重要，再来一道题目体会一下：
The importance of the ozone layer to terrestrial animals is that it entirely filters out some wavelengths of light but lets others through. Holes in the ozone layer and the dangers associated with these holes are well documented. However, one danger that has not been given sufficient attention is that these holes could lead to severe damage for animals of many species.
用下划线标出你认为是modifer的词
The importance of the ozone layer to terrestrial animals is that it entirely filters out some wavelengths of light but lets others through. Holes in the ozone layer and the dangers associated with these holes are well documented. However, one danger that has not been given sufficient attention is that these holes could lead to severe damage for animals of many species.
*: Words like “some,” “could,” and “many” encompass many different possibilities and are broad scope indicators. Words like “all”, “must” and “none” indicate a narrow scope.
来看看上面这个题干的整道题目：
The importance of the ozone layer to terrestrial animals is that it entirely filters out some wavelengths of light but lets others through. Holes in the ozone layer and the dangers associated with these holes are well documented. However, one danger that has not been given sufficient attention is that these holes could lead to severe damage for animals of many species.
Which one of the following is most strongly supported by the statements above. If they are true?
(A) All wavelengths of sunlight that can cause eye damage are filtered out by the ozone layer where it is intact.
(B) Few species of animals live on a part of the earth’s surface that is not threatened by holes in the ozone layer.
(C) Some species of animals have eyes that will not suffer any damage when exposed to unfiltered sunlight.
(D) A single wavelength of sunlight can cause severe damage to the eyes of most species of animals.
(E) Some wavelengths of sunlight that cause eye damage are more likely to reach the earth’s surface where there are holes in the ozone layer than where there are not.
分析：
(A) All这个词的范围很窄(narrow)，必须是一个red flag(警示信号)
(B) The stimulus stated that “many animal species could suffer severe eye damage”, and didn’t mention “live on unthreatened area”.
(C) stimulus里面只提到了many animal species，并不能够推出some species’ eyes will not suffer any damage. From a pure logic standpoint, “many” can include “all”.
(D) many与most也是不等的。
(E) Some wavelengths与stimulus中的filters out some wavelengths对应。
(1)可以从本题看出来，正确选项并没有结合所有的信息，只是fact sets的一些交集。
(2) many与all/most并不是一个范畴的概念，不可以替换。但是三个词都必须引起注意。
(3) pay strict attention to the modifiers used by the author.
5. Must Be True中可能正确的答案类型：
(1) Paraphrased Answers à test your ability to discern the author’s exact meaning. 要去主动想作者的意思、意图。
(2) Answers that are the sum of two or more stimulus statements (Combination Answers) à这一类可能涉及笔记法。但是熟练以后能记下的信息就多了，直接回去定位一下就行。变读边写反而分心
6. Must Be True中可能错误的答案类型：
(1) Could Be True or Likely to Be True Answers ----à 这个错题类型在RC中就会比较致命!不可小觑。
(2) Exaggerated Answers.
比如：stimulus里只说了”Some software vendors recently implemented more rigorous licensing procedures.” 而如果答案说”Most software vendors recently implemented more rigorous licensing procedures.”，则some is exaggerated to most.
再如:stimulus states, “Recent advances in the field of molecular biology make it likely that many school textbooks will be rewritten.” 答案如果说”Many school textbooks about molecular biology will be rewritten.”
(3) “New” Information Answers – out of scope.
(4) The Shell Game: 概念偷换.
(5) The opposite Answer. 与stimulus所述完全的fact相反
(6) The Reverse Answer.
例如: Stimulus: Many people have some type of security system in their home.
An incorrect Reverse Answer: Some people have many types of security systems in their home.
6. 加一个Must Be True的例题：
The increasing complexity of scientific inquiry has led to a proliferation of multiauthored technical articles. Reports of clinical trials involving patients from several hospitals are usually coauthored by physicians from each participating hospital. Likewise, physics papers reporting results from experiments using subsystems developed at various laboratories generally have authors from each laboratory.
If all of the statements above are true, which one of the following must be true?
(A) Clinical trials involving patients from several hospitals are never conducted solely by physicians from just one hospital.
(B) Most reports of clinical trials involving patients from several hospitals have multiple authors.
(C) When a technical article has multiple authors, they are usually from different institutions.
(D) Physics papers authored by researchers from multiple laboratories usually report results from experiments using subsystems developed at each laboratory.
(E) Most technical articles are authored solely by the researchers who conducted the experiments these articles report.
分析：
重点词：The increasing complexity of scientific inquiry has led to a proliferation of multiauthored technical articles. Reports of clinical trials involving patients from several hospitals are usually coauthored by physicians from each participating hospital. Likewise, physics papers reporting results from experiments using subsystems developed at various laboratories generally have authors from each laboratory.
(A) “conduct”属于new information(事实上Clinical trials和conduct其实是原文没有提到的，原文说的是报告谁来写，而不是谁来行使临床实验)。Never与not usually并不等效，Exaggerated answer。
(B) 正确答案。most与stimulus里面的usually相对应。
(C) Shell Game. Technical article与physics paper不一样。不过这里usually倒是对应的一致，增加了判断难度。
(D) Reverse answer.
The stimulus states, “Physics papers reporting results from experiments using subsystems developed at various laboratories generally have authors from each laboratory.”
Answer choice D states, “Physics papers authored by researchers from multiple laboratories usually report results from experiments using subsystems developed at each laboratory.”
*: authors from each laboratory have become researchers (authors) from multiple laboratories, and subsystems from various laboratories have become subsystems from each laboratory.
*: The pair also reverses logical position within the argument, as the stimulus sates that the experiments generally have authors from each laboratory and the answer choice states that the researchers usually report experiments from each laboratory.
*: generally与usually倒是对应
(E) 同C，Shell Game. Technical articles与physics范围不同。
(1) 时间一紧，或者记不住题目中说的内容、找不好题目中所阐述的逻辑，那么就立马找关键词。看1.modifier是否一致，2.是否有Shell Game或者Reverse answer两种迷惑手段，特别是选项与原文相近时。
(2) usually与most/generally相对应
7. 关于Stimulus Opinions与Assertions: When a stimulus contains only the opinions of others, then in a Must Be True question you can eliminate any answer choice that makes a flat assertion without reference to those opinions.
例题:
Some environmentalists question the prudence of exploiting features of the environment, arguing that there are no economic benefits to be gained from forests, mountains, or wetlands that no longer exist. Many environmentalists claim that because nature has intrinsic value. It would be wrong to destroy such features of the environment, even if the economic costs of doing so were outweighed by the economic costs of not doing so.
Which one of the following can be logically inferred from the passage?
(A) It is economically imprudent to exploit features of the environment.
(B) Some environmentalists appeal to a noneconomic justification in questioning the defensibility of exploiting features of the environment.
(C) Most environmentalists appeal to economic reason in questioning the defensibility of exploiting features of the environment.
(D) Many environmentalists provide only a noneconomic justification in questioning the defensibility of exploiting features of the environment.
(E) Even if there is no economic reason for protecting the environment, there is a sound noneconomic justification for doing so.
(A) (E) 原文只是表达了他人的观点，那么这种assertion就不可能是正确选项。
(B) 正确。Intrinsic value与noneconomic justification对应à同含义词替换
(C) most与some和many都不对应。
(D) only是个很关键的词。stimulus中并没有足够的evidence可以证明这个only.
8. Must Be True题不是argument本来就比较难prephrasing一点。所以如果一下子prephrase不出来不要担心。
我们还有四把武器：”修饰词”, ”Shell Game”, ”Reverse Answer”, ”新信息”。还有一个肯定正确答案的武器：同义词替换。
9. tend to 能与 usually/ in general相对应
Often与most不能相对应，因为频率不同。
10.常考numbers and percentages和充分必要
Chapter 5: Main Point Questions
1. Main Point题在阅读理解中出现得比较多。做好Main Point题对有argument类型题invaluable，比如Weaken, Strenghten等。
2. Two incorrect Answer Types:
(1) Answers that are true but do not encapsulate the author’s point.
(2) Answers that repeat premises of the argument.
3. Answers that paraphrase the conclusion are correct in Main Point questions.
Chapter 6: Weaken Questions
1. Unlike Must Be True questions, Weaken answer choices can bring into consideration information outside of or tangential to the stimulus. (新信息是允许的)
2. Be sure to actively consider the range of possible answers before proceeding to the answer choices.
3. When evaluating an answer, ask yourself, “Would this answer choice make the author reconsider his or her position or force the author to respond?”
4. The correct answer often shows that the conclusion does not necessarily follow from the premises even if the premises are true. Answers that weaken the argument’s conclusion will attack assumptions made by the author.
5. weaken题分析两步走:
(1) to focus on the conclusion(最重要的原则) and how the author arrived at the conclusion.
(2) to personalize the argument. When analyzing the author’s argument, imagine how you would respond if you were talking directly to the author. Would you use answer choice (A) or would you prefer answer choice (B)? Personalizing helps you see the argument from a very involved perspective.
6. Three Incorrect Answer Traps:
(1) Opposite Answers
(2) Shell Game Answers
(3) Out of Scope Answers – Irrelevant Answers.
7. Prephrasing is often easier with Weaken questions than with some other question types.
8. 若题干很难懂，或问题很少见，出题人就喜欢把正确答案放到(A)。
9. 必须对每一个选项都分析过去，宁愿再多花10秒。
10. Weaken, Strengthen, assumption等题型中多有涉及到Causality(Cause and Effect Reasoning)和Numbers and Percentages的问题，以后要统一讲到。
*：除了causality, numbers and percentages之外的正确答案类型：
(1) 原文前提和结论关系不密切：正确选项直接weaken结论
(2) 条件性结论，conditional conclusion。结论带条件，weaken的方法是举例或提供有关信息。
(3) 原文是类比，weaken方法是两者本质不同(指出任何的dissimilarity就行)。
(4) 调查：有效性受质疑。
11. 例题：
The five senses have traditionally been viewed as distinct yet complementary. Each sense is thought to have its own range of stimuli that are incapable of stimulating the other senses. However, recent research has discovered that some people taste a banana and claim that they are tasting blue, or see a color and say that it has a specific smell. This shows that such people, called synesthesiacs, have senses that do not respect the usual boundaries between the five recognized senses.
Which one of the following statements, if true, most seriously weakens the argument?
(A) Synesthesiacs demonstrates a general systematic impairment in their ability to use and understand words.
(B) Recent evidence strongly suggests that there are other senses besides sight, touch, smell, hearing, and taste.
(C) The particular ways in which sensory experiences overlap in synesthesiacs follow a definite pattern.
(D) The synesthetic phenomenon has been described in the legends of various cultures.
(E) Synesthesiacs can be temporarily rid of their synesthetic experiences by the use of drugs.
分析：
(A) 正确答案。不是很容易在第一眼判断出来是正确答案，那么就用排除法。不是很喜欢stimulus中的respect与此选项中的impairment。他因，非A导致B，而是C导致B。这个其实也算是因果题。
(B) irrelevant/out of scope. 这个选项比较迷惑，一开始可以先记为contender。但是other senses是什么并没有说，与sensory overlap没有直接关系。排除
(C) supportàopposite answer
(D) irrelevant / out of scope legends of various cultures一看就无关。
(E) support à opposite answer
例2. Archaeologist: A skeleton of a North American mastodon that became extinct at the peak of the Ice Age was recently discovered. It contains a human-made projectile dissimilar to any found in that part of Eurasia closet to North America. Thus, since Eurasians did not settle in North America until shortly before the peak of the Ice Age, the first Eurasian settlers in North America probably came from a more distant part of Eurasia.
Which one of the following, if true, most seriously weakens the archaeologist’s argument?
(A) The projectile found in the mastodon does not resemble any that were used in Eurasia before or during the Ice Age.
(B) The people who occupied the Eurasian area closet to North America remained nomadic throughout the Ice Age.
(C) The skeleton of a bear from the same place and time as the mastodon skeleton contains a similar projectile.
(D) Other North American artifacts from the peak of the Ice Age are similar to ones from the same time found in more distant parts of Eurasia.
(E) Climatic conditions in North America just before the Ice Age were more conductive to human habitation than were those in the part of Eurasia closet to North America at that time.
(A)正确选项。The answer hurts the argument by indicating that the projectile is apparently not Eurasian, suggesting that the first Eurasian settlers could have come from any part of Eurasia, including the area closet to North America. 专注的是conclusion，攻击的是reasoning，即premise到conclusion的过程。这应该就是Lawyer说的“条件性结论—提供有关信息，或举反例进行weaken。”
(B) Irrelevant – out of scope. Some students attempt to conclude that since the people were nomadic, they could have moved to areas farther away and found projectiles like the one in the mastodon. But they did not necessarily occupy other areas and this answer does not hurt the argument. 不能中间还架构一个假定。
(C) opposite.
(D) opposite
(E) opposite
例3：第(3)类weaken法(原文是类比，weaken方法是两者本质不同(指出任何的dissimilarity就行))：
104. Although the discount stores in Goreville’s central shopping district are expected to close within five years as a result of competition from a SpendLess discount department store that just opened, those locations will not stay vacant for long. In the five years since the opening of Colson’s, a nondiscount department store, a new store has opened at the location of every store in the shopping district that closed because it could not compete with Colson’s.
Which of the following, if true, most seriously weakens the argument?
(A) Many customers of Colson’s are expected to do less shopping there than they did before the SpendLess store opened.
(B) Increasingly, the stores that have opened in the central shopping district since Colson’s opened have been discount stores.
(C) At present, the central shopping district has as many stores operating in it as it ever had.
(D) Over the course of the next five years, it is expected that Goreville’s population will grow at a faster rate than it has for the past several decades.
(E) Many stores in the central shopping district sell types of merchandise that are not available at either SpendLess or Colson’s.
排除法是比较简单的。
不过正向推导或许这道题目会让人迷糊一下，以后遇到这种前后突然说不同话的题，就要发现是一个原文求同，weaken寻异的题目。
原文翻译：
虽然GC预计在五年内会因为SDD(Spendless Discount Department Store)的竞争而关掉，不过GC关掉以后空出的地方不会留空很久的。CND(Colson's nondiscount department store)开出来的第五年，一个新的商店已经在原先因为无法跟CND竞争而倒闭的商店的location开出了店面。
这段文字的conclusion是第一句：GC关掉以后空出的地方不会留空很久的。
前半段与后半段形成一个错误类比。两个items原文求同，那么我们就要寻异，指出两个items之间无法类比：
选项B指出：
第二个item是说CND对DD(discount store)没有长期的抵制，DD持续增加着(增加的全部都是DD)，潜在含义是人们需要DD。第一个item里面SDD对其他店(非DD店，因为如果是DD店，没有必要应该是一个department store了，很大的)没有长期的抵制，潜在含义是人们不那么需要DD。
所以两个items说明的东东是不一样的，不可以类比。
换句话讲就是第二个item想说明的是DD重要，第一个items想说的是DD不重要。
*：其实对类比论述的削弱，答案肯定都是这样子明显的。所以类比型arugment的难度在于“我们一下子没看出是类比题。”
有一个小方法就是：如果前后句找不到关系，那么不是类比题，就是explain题。
Chapter 7: Cause and Effect Reasoning
1. Causality in the Conclusion: If the causal statement is the conclusion, then the reasoning is flawed. – flaw in reasoning.
Causality in the Premise: If the causal statement is the premise, then the argument may be flawed. (是属于其他问题，而不是causality出问题了)
2. Situations that can lead to errors of Causality:
(1) One event occurs before another 前后发生非因果
(2) Two (or more) events occurs at the same time 同时发生非因果
3. How to attack a causal conclusion:
Whenever you identify a causal relationship in the conclusion of a GMAT problem, immediately prepare to either weaken or strengthen the argument. à Causality的题目很容易prephrase。看到因果就要开始想weaken或support。
1. Find an alternate cause for the sated effect. 题说 AàB，我说CàB。
2. Show that even when the cause occurs, the effect does not occur. 有A却无B。
3. Show that although the effect occurs, the cause did not occur. 无A也有B。
4. Show that the stated relationship is reversed. 乾坤腾，不是AàB，而是BàA。(多针对于同时发生非因果)
5. Autocorrelation. 不是AàB，是A，B本来就关联。
6. Show that a statistical problem exists with the data used to make the causal statement. If the data used to make a causal statement are in error, then the validity of the causal claim is in question. 显示因果关系的统计资料有问题。
4. 例题1：
Most antidepressant drugs cause weight gain. While dieting can help reduce the amount of weight gained while taking such antidepressants, some weight gain is unlikely to be preventable.
The information above most strongly supports which one of the following?
(A) A physician should not prescribe any antidepressant drug for a patient if that patient is overweight.
(B) People who are trying to lose weight should not ask their doctors for an antidepressant drug.
(C) At least some patients taking antidepressant drugs gain weight as a result of taking them.
(D) The weight gain experienced by patients taking antidepressant drugs should be attributed to lack of dieting.
(E) All patient taking antidepressant drugs should diet to maintain their weight.
分析：
Must Be True题第一步还是识别stimulus中的关键词。Most, help reduce(区别与reduce), such, some。
(A)中的any和(B)中的in antidepressant drug和(E)中的All都过于exaggerated了。
(C)正确
(D) opposite answer.
5. 两道训练找关键词来prephrase的题目：
例题2：
Violent crime in this town is becoming a serious problem. Compared to last year, local law enforcement agencies have responded to 17 percent more calls involving violent crimes, showing that the average citizen of this town is more likely thanever to become a victim of a violent crime.
Which one of the following, if true, most seriously weakens the argument?
(A) The town’s overall crime rate appears to have risen slightly this year compared to the same period last year.
(B) In general, persons under the age of 65 are less likely to be victims of violent crimes than persons over the age of 65.
(C) As a result of the town’s community outreach programs, more people than ever are willing to report violent crimes to the proper authorities.
(D) In response to worries about violent crime, the town has recently opened a community center providing supervised activities for teenagers.
(E) Community officials have shown that a relatively small number of repeat offenders commit the majority of violent crimes in the town.
分析：Causality的题目很容易prephrase。看到因果就要开始想weaken或support。
这句话看下，哪个词是找出causal flaw的关键词。
1.average要敏感
2.前后有偷换概念。
3.作者拿来跟victim对应而产生概念偷换的词-->calls，也就是关键词。
那么预测一下答案：
上报犯罪多了，不是犯罪本身增加，而是上报的人多了
于是秒杀C。
例题3：
Unlike newspapers in the old days, today's newspapers and televised news programs are full of stories about murders and assaults in our city. One can only conclude from this change that violent crime is now out of control, and, to be safe from personal attack, one should not leave one's home except for absolute necessities.
Which one of the following, if true, would cast the most serious doubt on the conclusion?
(A) Newspapers and televised news programs have more comprehensive coverage of violent.
(B) National data show that violent crime is out of control everywhere, not just in the author’s city.
(C) Police records show that people experience more violent crimes in their own neighborhoods than they do outside their neighborhoods.
(D) Murder comprised a larger proportion of violent crimes in the old days than it does today.
(E) News magazines play a more important role today in informing the public about crime than they did in the old days.
跟上面那个题目有一个共同点，共同的pattern
第一个那道题目可以预测出来答案了，第二个试试看?
媒体的犯罪报道多了，不代表犯罪就真的更多了，也许是媒体比以前跟关注犯罪了
那么第二题的关键词是什么呢?也就是一个跟第一题里面的call一样的一个词。对了，就是stories。
依次，秒杀选A。
*: 当然在分析题目的时候还是应该看一下错误选项的。B是opposite，C,D,E都是out of scope/irrelevant。
6. 例4：
Medical researcher: As expected, records covering the last four years of ten major hospitals indicate that babies born prematurely were more likely to have low birth weights and to suffer from health problems than were babies not born prematurely. These records also indicate that mothers who had received adequate prenatal care were less likely to have low birth weight babies than were mothers who had received inadequate prenatal care. Adequate prenatal care, therefore, significantly decreases the risk of low birth weight babies.
Which one of the following, if true, most weakens the medical researcher’s argument?
(A) The hospital records indicate that many babies that are born with normal birth weights are born to mothers who had inadequate prenatal care.
(B) Mothers giving birth prematurely are routinely classified by hospitals as having received inadequate prenatal care when the record of that care is not available.
(C) The hospital records indicate that low birth weight babies were routinely classified as having been born prematurely.
(D) Some babies not born prematurely, whose mothers received adequate prenatal care, have low birth weights.
(E) Women who receive adequate prenatal care are less likely to give birth prematurely than are women who do not receive adequate prenatal care.
分析：
这道题目相当的复杂，读到后面都忘了前面更不用说结合诸多permise来prephrase一个weaken的方法了。
针对复杂题有一个很好的方法就是：根据有关无关来判断，就算没有理清关系还是可以的。
这道题目的正确答案是典型的showing statistical problem.
看到record这个关键字，再加行causality就应该想到了statistical problem，因为是GMAT惯用伎俩。
A,C,D都无关，E是加强。排除四个选B。
A和D的错误进一步分析：A中的many和D中的some都是符合stimulus中的概率表达less likely to的。
*：概率表达词也必须特别重视，包括be likely to.
Chapter 8: Strengthen, and Assumption Questions.
1. Arguments that contain analogies or use surveys rely upon the validity of those analogies and surveys. Answer choices that strengthen the analogy or survey, or establish their soundness, are usually correct.
2. Three Incorrect Answer Traps – Strengthen:
(1) Opposite Answers.
(2) Shell Game Answers. In Strengthen questions, the Shell Game is usually used to support a conclusion that is similar to, but slightly different from, the one presented in the stimulus.
(3) Out of Scope Answers. – Unrelated, irrelevant.
3. Strengthen题中正确选项的几种类型(与weaken一一对应)(causality在第5条中说到)：
(1) 原文前提和结论关系不密切，正确选项支持结论
(2) 原文是类比：support方式为两者本质相同
(3) 调查：有效性不受怀疑。(被调查对象有代表性等等)
(4) assumption类的支持(当support是necessary必要条件时)à可以架桥、说明达到结论效果的方式、手段。
(5) 有A才有B，然后说A确实存在。
4 例题1：
Statistician: A financial magazine claimed that its survey of its subscribers showed that North Americans are more concerned about their personal finances than about politics. One question was:” Which do you think about more: politics or the joy of earning money?” This question is clearly biased. Also, the readers of the magazine are a self-selecting sample. Thus, there is reason to be skeptical about the conclusion drawn in the magazine’s survey.
Each of the following, if true, would strengthen the statistician’s argument EXCEPT:
(A) The credibility of the magazine has been called into question on a number of occasions.
(B) The conclusions drawn in most magazine surveys have eventually been disproved.
(C) Other surveys suggest that North Americans are just as concerned about politics as they are about finances.
(D) There is reason to be skeptical about the results of surveys that are biased and unrepresentative.
(E) Other surveys suggest that North Americans are concerned not only with politics and finances, but also with social issues.
分析：
本题经典之处在于，把survey的四个漏洞都给补上了。A, B, C, D分别表示了对survey四种不同的weaken角度(也就是对statistician的support)，加上statistician说的两个角度: One question was biased， The sample was self selecting，一共六个角度。而E是无关。
5. Strengthen中的Causality问题：
(A) Eliminate any alternate causes for the stated effect. No + 他因
(B) Show that when the cause occurs, the effect occurs. 有A就有B.
(C) Show that when the cause does not occur, the effect does not occur. 无A就无B.
(D) Eliminate the possibility that the stated relationship is reversed. 不乾坤腾了。
(E) Show that the data used to make the causal statement are accurate, or eliminate possible problems with the data. 强调因果关系的资料是正确的。
6. 例题2：
Amphibian populations are declining in numbers worldwide. Not coincidentally, the earth’s ozone layer has been continuously depleted throughout the last 50 years. Atmospheric ozone blocks UV-B, a type of ultraviolet radiation that is continuously produced by the sun, and which can damage genes. Because amphibians lack hair, hide, or feathers to shield them, they are particular vulnerable to UV-B radiation. In addition, their gelatinous eggs lack the protection of leathery or hard shells. Thus, the primary cause of the declining amphibian population is the depletion of the ozone layer.
Each f the following, if true, would strengthen the argument EXCEPT:
(A) Of the various types of radiation blocked by atmospheric ozone, UV-B is the only type that can damage genes.
(B) Amphibian populations are declining far more rapidly than are the populations of nonamphibian species whose tissues and eggs have more natural protection from UV-B.
(C) Atmospheric ozone has been significantly depleted above all the areas of the world in which amphibian populations are declining.
(D) The natural habitat of amphibians has not become smaller over the past century.
(E) Amphibian populations have declined continuously for the last 50 years.
分析：
(A) 正确答案。因为是无关的
(B) 无A就无B。错误代号type C。
(C) 有A就有B。错误代号type B。
(D) Had the natural habitat become smaller over the years have offered an alternate explanation for the decline in the amphibian population. By eliminating the possibility of habitat shrinkage, the stated cause in the argument is strengthened. 即amphibian的数量减少不是因为habitat减少了。No + 他因。错误代号Type A。
(E) 强调因果关系的资料是正确的，错误代号Type E。
7. 例题3：
Medical doctor: Sleep deprivation is the cause of many social ills, ranging from irritability to potentially dangerous instances of impaired from sleep deprivation to some degree. Therefore we should restructure the workday to allow people flexibility in scheduling their work hours.
Which one of the following, if true, would most strengthen the medical doctor’s argument?
(A) The primary cause of sleep deprivation is overwork.
(B) Employees would get more sleep if they had greater latitude in scheduling their work hours.
(C) Individuals vary widely in the amount of sleep they require.
(D) More people would suffer from sleep deprivation today than did in the past if the average number of hours worked per week had not decreased.
(E) The extent of one’s sleep deprivation is proportional to the length of one’s workday.
分析：
Gap题解法：Always, whenever you see a gap in the argument, you can strengthen the argument by eliminating that gap.
(A) 关键词overwork. Shell Game.
(B) 正确选项
(C) opposite answer. weaken，最多是Out of Scope
(D) 注意had decreased，说明过去就已经reduce workdays per week了。
In parts of South America, vitamin-A deficiency is a serious health problem, especially among children. In one region, agriculturists hope to improve nutrition by encouraging farmers to plant a new variety of sweet potato called SPK004 that is rich in betacarotene, which the body converts into vitamin A. The plan has good chances of success, since sweet potato is a staple of the region’s diet and agriculture, and the varieties currently grown contain little beta-carotene.
Which of the following, if true, most strongly supports the prediction that the plan will succeed?
A. There are other vegetables currently grown in the region that contain more beta-carotene than the currently cultivated varieties of sweet potato do.
B. The flesh of SPK004 differs from that of the currently cultivated sweet potatoes in color and texture, so traditional foods would look somewhat different when prepared from SPK004.
C. For successful cultivation of SPK004, a soil significantly richer in nitrogen is needed than is needed for the varieties of sweet potato currently cultivated in the region.
D. There are no other varieties of sweet potato that are significantly richer in beta-carotene than SPK004 is.
E. The currently cultivated varieties of sweet potato contain no important nutrients that SPK004 lacks.
分析：
(assumption类的支持)
按照assumption类题目的做法。这个题目就是assumption中的defender (no + alternative). 选E。
例题：
Almost every modern kitchen today is equipped with a microwave oven, mainly because microwave ovens offer a fast and convenient way of cooking and reheating food. Indeed, it has become a standard appliance in most households. Studies have shown, however, that microwave ovens are not completely safe and their use has occasionally resulted in serious injury. Because of this, some consumer advocates argue that microwave ovens should not be so readily accepted as a standard appliance until they can be certified to be completely safe.
Which of the following, if true, would most strengthen the argument of the consumer advocates?
A. Microwave ovens have taken much of the joy out of cooking.
B. There have been many reported incidences of people who have been scalded by liquids superheated in microwave ovens.
C. Absolute safety is the only criterion by which an appliance should be judged to be acceptable as "standard."
D. There is no such thing as a completely safe appliance.
E. Stoves and ovens that use natural gas consume energy much more efficiently than microwave ovens
有A才有B，support方式是A存在。而且不能主观判断看到C中absolute就认为是错的(现实世界中没有任何东西是absolutely safe的，可是那是现实世界，如果这么判断就带入了主观思想了)，而且C里面的absolute和结论中的completely不知道有多配!
所以选C很好。而对于B，并不是微波炉使人受的伤，而是liquid产生的。而liquid是微波炉加热的而已。这个很tricky.
例题：
Analyst: The pace of technological development brings a constant stream of new devices to the market, and many of them enjoy commercial success. But announcing new technology too soon after the introduction of a successful device can backfire. Once consumers hear about the new device, they may stop buying the one currently on sale. So, if a company wishes to announce the upcoming sale of a new device, it should wait until purchases of the old device have begun to decline.
Which of the following, if true, would best support the analyst's main assertion?
A) New technology often becomes less expensive after an initial surge in sales.
B) Media outlets, such as television programs and magazines, often report on the planned introduction of new devices while the sales of old devices are still strong.
C) Many consumers are unable to determine whether new technology is superior to current technology.
D) Surveys have shown that some consumers make only one or two technology purchases per year, whereas others make more frequent purchases.
E) Consumers tend to be loyal to technology companies whose products they enjoy using.
C选项乍看非常有关，可惜是opposite，B选项看着不像，但是却说了下大众确实能够接受到新产品的信息，也就是confirm了premise的正确性。(Show that the data used to make the causal statement are accurate, or eliminate possible problems with the data. 强调因果关系的资料是正确的。)
================================== assumption分割线 ===================================
8. Assumption: If an answer choice contains a statement that the author might only think could be true, or if the statement contains additional information that the author is not committed to, then the answer is incorrect.
9. Assumption answer choices cannot contain extraneous information (外延信息). For example, let us say that an argument requires the assumption “all dogs are intelligent.” The correct answer could be that statement, or even a subset statement such as “all black dogs are intelligent” or “all large dogs are intelligent”. But, additional information would rule out the answer, as in the following case:” All dogs and cats are intelligent.” The additional information about cats is not part of the author’s assumption, and would make the answer choice incorrect.
10. On the GMAT, Assumptions play one of two roles -- the Supporter or the Defender.
(1) The Supporter role is the traditional linking role, where an assumption connects the pieces of the argument. Supporter assumptions on the GMAT are often relatively easy for student to identify because they can see the gap in the argument. (即gap题)
(2) The defender role is entirely different, and Defender assumptions protect the argument by eliminating ideas that could weaken the argument. (即no + 他因题)
*: 猜测：gap题的conclusion里一定会出现new or rogue element吗? -- 暂时先接受一定会出现，待验证
*：If at first glance an argument does not seem to have any holes, this would suggest a Defender answer is coming.
11. Defender题的一个例题：
In Western economics, more energy is used to operate buildings than to operate transportation. Much of the decline in energy consumption since the oil crisis of 1973 is due to more efficient use of energy in homes and offices. New building technologies, which make lighting, heating, and ventilation systems more efficient, have cut billions of dollars from energy bills in the West. Since energy savings from these efficiencies save several billion dollars per year today, we can conclude that 50 to 100 years from now they will save more than $200 billion per year (calculated in current dollars).
On which one of the following assumption does the argument rely?
(A) Technology used to make buildings energy efficient will not become prohibitively expensive over the next century.
(B) Another oil crisis will occur in the next 50 to 100 years.
(C) Buildings will gradually become a less important consumer of energy than transportation.
(D)Energy bills in the West will be $200 billion lower in the next 50 to 100 years.
(E) Energy-efficient technologies based on new scientific principles will be introduced in the next 50 to 100 years.
分析：
B: irrelevant
C无关比较点
D: Energy bills范围太大，Out of scope.
剩下A, E不是很好选，有两个方法。
1. 取非可以发现E不是weaken，而A是。则迅速选A
2. E: The argument is ABOUT CURRRENT TECHNOLOGIES SAVING MONEY IN THE FUTURE. The author does not make an assumption regarding new technologies being introduced in the future.
(1) assumption题在最后3-2 split之后通过取非排除其中一个这样速度更快。如果真的对照原文再仔细看，速度太慢了。
12. Only a few types of GMAT questions allow you to double-check your answer. Assumption questions are one of those types.
(1) 取非的一步要在缩小选项范围之后再做。
(2) gap题，即supporter题也可以取非，但太简单没必要取非。
试试看，把下面这个句子取非：
Exactly one police car will reach the scene in time.
à
Not exactly one police car will reach the scene in time.
Typically, there are two ways to negate a phrase containing the words “only one” or “exactly one.”(这一类取非题比较特殊，切记) One possibility is to use the term “none” and the other possibility is to use the phrase “more than one.” Both are logical negations since you are attempting to negate a statement where something occurred a precise number of times. In this case, any statement that differs in number from the original statement will be negation. (此题中可以发现，取非时，否定的不一定是谓语动词，因为有时对谓语动词取非没有意义。)
13. 在Assumption题中：
(1) 特别重视有”at least one” or “at least some”这种字眼的选项，极有可能是正确的。这种选项立马用none来替换”at least one” or “at least some”进行取非作进一步验证。
(2) Avoid answers that claim an idea was the most important consideration for the author. These answers typically use constructions such as “the primary purpose”,
