犇犇奉献，逻辑几类题型的见解和思录，持续更新中~

犇犇

犇犇咨询团成立以来也有半年了，答过疑，教过考生，做过jj讨论稿，以后会不定期的发布一些gmat的逻辑见解和思路，望指教~
以后的帖子会按照削弱、加强、假设、评价、归纳、解释、填空、黑脸的顺序来一类类更新，敬请关注，有问题大家也可以一起讨论

人在美国，暂时没时间更新
有问题可以加qq，303932934，尽力帮大家解决

请关注持续更新的数学资料大奉献：http://forum.chasedream.com/GMAT_Math/thread-560874-1-1.html 谢谢犇犇-【肛裂】同学


这个是以后当月的gmat数学狗狗讨论群：136480565  
加的同学注明cder and 考试日期，学术群，切勿太水~


OG12中的削弱题：1、5、15、23、30、35、36、40、45、60、63、73、75、83、87、90、81、88、96、104、111、114、116、118、120、123



下面选取几道，个人觉得有代表性的削弱题先举例说明，然后总结一下



OG12第23题

A drug that is highly effective in treating many types of infection can, at present, be obtained only from the bark of the ibora, a tree that is quite rare in the wild. It takes the bark of 5,000 trees to make one kilogram of the drug. It follows, therefore, that continued production of the drug must inevitably lead to the ibora’s extinction.

Which of the following, if true, most seriously weakens the argument above?


1.先不看选项，来看题干。做逻辑题首先要看问题，看看问题中有用的信息。这一题，问题只能说明本道题问的是削弱。那么，看到weaken这个字眼出现，知道了是削弱题，脑海中立马要反应过来，题干的结论是错的（虽然说得有点儿绝对化，但是目的是反驳这个argument，那就干脆认为这个argument的最终结果是错的），然后找漏洞进行反驳。至于这个叙述方式到底是什么，我个人觉得不需要太多关注，不管是因果型、条件型、类比型还是调查，最关键的是发现题目的漏洞，这个时候逻辑链就能派上用场了。

咳咳，废话说了很多，进入正题，看看题干的结论到底是什么

2.Therefore点出了结论：continued production of the drug must inevitably lead to the ibora’s extinction. 看到结论直接默认，持续的drug生产不会导致ibora灭绝。

3.找到了结论，那么看这个题干是如何推理出结论的，也就是逻辑链。

生产1kg某种drug需要5000棵稀有的wild ibora为原料à持续的drug生产则ibora灭绝

4.得出了逻辑链，就可以推测问题的源头了

从后往前倒推：持续的drug生产不会导致ibora灭绝à原料不仅限于wild ibora。

5.再看答案，呼之欲出啊了。

(A) The drug made from ibora bark is dispensed to doctors from a central authority.

(B) The drug made from ibora bark is expensive to produce.

(C) The leaves of the ibora are used in a number of medical products.

(D)The ibora can be propagated from cuttings and grown under cultivation. D

(E) The ibora generally grows in largely inaccessible places.

关于E选项为什么错。个人感觉因为是continued production意思就是已然在生产了，和能不能取得无关了。

再则，大家寻思一下，如果这道题目变成assumption呢？答案是什么呢？



OG12第30题

Robot satellites relay important communications and identify weather patterns. Because the satellites can be repaired only in orbit, astronauts are needed to repair them. Without repairs, the satellites would eventually malfunction. Therefore, space flights carrying astronauts must continue.

Which of the following, if true, would most seriously weaken the argument above


我的思考过程：

1.看问题，削弱，无其他关键信息

2.找结论：space flights carrying astronauts must continue

3.将结论否定之：space flights carrying astronauts may not continue

4.逻辑链：satellites只能在轨道上修理不修就坏了à astronauts are neededà space flights carrying astronauts must continue

5.反推：space flights carrying astronauts may not continueà astronauts are not needed

6.找到最终需要反驳的源头了：astronauts are not needed，找个理由说明为什么astronaut不需要呗。

7.找答案↓

(A) Satellites falling from orbit because of malfunctions burn up in the atmosphere.

(B) Although satellites are indispensable in the identification of weather patterns, weather forecasters also make some use of computer projections to identify weather patterns.

(C) The government, responding to public pressure,has decided to cut the budget for space flights and put more money into social welfare programs.

(D) Repair of satellites requires heavy equipment, which adds to the amount of fuel needed to lift a spaceship carrying astronauts into orbit.

(E) Technical obsolescence of robot satellites makes repairing them more costly and less practical than sending new, improved satellites into orbit.



OG12第40题

In the last decade there has been a significant decrease in coffee consumption. During this same time, there has been increasing publicity about the adverse long-term effects on health of the caffeine in coffee. Therefore, the decrease in coffee consumption must have been caused by consumers’ awareness of the harmful effects of caffeine.

Which of the following, if true, most seriously calls into question the explanation above?


1.看问题，削弱，没有其他关键信息

2.找结论：the decrease in coffee consumption must have been caused by consumers’ awareness of the harmful effects of caffeine.

3.否定结论：the decrease in coffee consumption may not have been caused by consumers’ awareness of the harmful effects of caffeine.

4.逻辑链：increasing publicity about the adverse long-term effects on health of the caffeine in coffeeàconsumers’ awareness of the harmful effects of caffeineàdecrease in coffee consumption

5.反推，其实这一题不需要反推，很容易，甚至连逻辑链都不需要推，既然否定完结论后出现的结果是：the decrease in coffee consumption may not have been caused by consumers’ awareness of the harmful effects of caffeine，那就必然寻找他因了。找到别的原因说明the decrease in coffee consumption咯。

6.寻找他因↓

(A) On average, people consume 30 percent less coffee today than they did 10 years ago.

(B) Heavy coffee drinkers may have mild withdrawal symptoms, such as headaches, for a day or so after significantly decreasing their coffee consumption.

(C) Sales of specialty types of coffee have held steady as sales of regular brands have declined.

(D) The consumption of fruit juices and caffeine-free herbal teas has increased over the past decade.

(E)Coffee prices increased steadily in the past decade because of unusually severe frosts in coffee-growing nations.

再次，请大家看看，哪一个选项是支持结论的答案呢？



总结

整体的做题过程就是：1. 看问题，注意题型，有没有关键信息

2. 找结论

3. 自动否定找到的结论

4. 推理逻辑链

5. 用否定的结论反推，找到出问题的源头，也就是weaken point

6. 找到了weaken的点，看选项



PS：其实逻辑题对于阅读的理解还有思维过程有很高的要求，可以说，sc经过大量的做题和总结、归纳之后可以很快的提高；rc考的是阅读速度和快读的理解，和平时积累不可分割，同时机经帮助较大。而对于逻辑来说，要是基础不行，读不懂题，自然悲剧；读懂了题，找不到突破点，同样容易悲剧，这是思维过程的出现问题；同时，逻辑的机经是双刃剑，没有一个正确思维的同学，看了逻辑机经最终只会顾着背答案，考试容易迷糊，逻辑寂静需要自己思考整理，最好把完整的寂静都推理一下逻辑链，思考一下答案方向。

GWD30-Q32
A major chemical spill occurred five years ago at Baker’s Beach, the world’s sole nesting ground for Merrick sea turtles, and prevented nearly all the eggs laid that year from hatching.Yet the number of adult female Merricks returning to lay their eggs at Baker’s Beach has actually increased somewhat since five years ago.Clearly, environmentalists’ prediction that the world’s Merrickpopulation would decline as a result of the spill has proven unfounded.
Which of the following, if true, most seriously undermines the argument offered in refutation of the environmentalists’ prediction?

1. 看问题，削弱题，但是有关键信息，要看懂：反驳对于环境学家预测的反驳，也就是说支持环境学家的结论

2. 找结论：environmentalists’ prediction that the world’s Merrick population would decline as a result of the spill has proven unfounded

3. 否定结论：environmentalists’ prediction that the world’s Merrick population would decline as a result of the spill has proven founded

4. 逻辑链：（1）5年前的污染导致唯一的海龟产卵地的蛋不能孵化

 （2）母海龟数量增加à因为污染海龟数量减少的预测是错误的

5. 反推：出现了两个原因，（1）（2）两个原因是相冲突的，由（1）推出了结论，现在要反驳结论，结论取非后必然是可以直接推导到（2）也就是：因为污染海龟数量减少的预测是对的à5年前的污染导致唯一的海龟产卵地的蛋不能孵化
剩下的工作就是来解释（1）（2）会相冲突的原因，同时反推出来的（2）是正确的，解释（1）产生差异的原因

6. 找答案，为什么受到污染了，母海龟数量还会增加呢

A.The chemical spill five years ago occurred at a time when there were neither Merrick sea turtles nor Merrick sea turtle eggs on Baker’s Beach.

B.Female Merrick sea turtles begin returning to Baker’s Beach to lay their eggs when they are ten years old.

C.Under normal conditions, only a small proportion of hatchling female Merrick sea turtles survive in the ocean until adulthood and return to lay their eggs at Baker’s Beach.

D.Environmental pressures unrelated to the chemical spill have caused a significant decline in the population of one of the several species of sea birds that prey on Merrick sea turtle eggs.

E.After the chemical spill, an environmental group rejected a proposal to increase the Merrick sea turtle population by transferring eggs from Baker’s Beach to nearby beaches that had not been affected by the spill.

这题选B，两个时间差异说明了为什么母海龟的数量还会增加：因为10年前没有受到污染！现在的蛋受到污染不能孵化了，以后海龟的数量必然会减少！环境专家的预测是对的。

金轩宸

相当经典

Michiko54

谢谢LZ~~等待LZ更新哈~~一直在摸索最适合自己的逻辑方法~~~

stella8625

这个方法真好用！！感谢！！

zhengzoe

等楼主更新啊~

youzigege

lz快更新啊~~~
再赞一下！

janetking

谢谢LZ!!!我想问一下关于assumption题的思路 非常谢谢！

lidan891103

先顶个~

youzigege

强赞强关注啊！！

fionaz426

好贴，必成经典，继续加油啊