讨论型文章的核心考点是讨论中得出的因果关系，因此其重心在于因果。下面我们参照《GMAT考试官方指南(第10版)》中的实例，来体会一下GMAT阅读文章中以“因果”为核心的解题思路。本文就因果关系先为大家介绍一下GMAT阅读解题思路。
因果关系GMAT阅读解题思路例1：(共6道题，在此仅将其中3道作为例证)Although genetic mutations inbac-teria and viruses can lead to epidemics,some epidemics are caused by bacteriaand viruses that have undergone no sig-nificantgeneticchange.Inanalyzingthelatter,scientists have discovered theimportance of social and ecological fac-tors to epidemics.Poliomyelitis,forexample,emerged as an epidemic in theUnitedStatesinthetwentiethcentury;bythen,modern sanitation was able to de-lay exposure to polio until adolescenceor adulthood,at which time polio infec-tionproducedparalysis.Previously,in-fectionhadoccurredduringinfancy,whenit typically provided lifelong immunitywithout paralysis.Thus,the hygienethat helped prevent typhoid epidemicsindirectly fostered a paralytic polioepidemic.Another example is Lymedisease,which is caused by bacteriathat are transmitted by deer ticks.Itoccurred only sporadically during thelate nineteenth century but has recentlybecome prevalent in parts of the UnitedStates,largely due to anincreaseinthedeer population that occurred simulta-neously with the growth of the suburbs
New Oriental Englishand increased outdoor recreational ac-tivitiesinthedeer'shabitat.Similarly,anoutbreak of dengue hemorrhagic feverbecame an epidemic in Asia in the 1950'sbecause of ecological changes thatcaused Aedes aegypti,the mosquitothat transmits the dengue virus,toproliferate.The stage is now set in theUnited States,for a dengue epidemicbecause of theinadvertentintroductionand wide dissemination of anothermosquito,Aedes albopictus.
总体思路：本文提出了一种观点：有些流行病是由社会和生态因素造成的。接着下文举了三个例子以及四个因果关系来支持此观点。这时我们首先要明确逻辑考点，即四个因果关系中一定会出题，因此文中四个因果关系词或短语后面的句子一定要细读，而其他部分略读即可。
在明确了这个基本思路以后，我们来详细分析几道考题：
1.The passage suggests that a lackof modern sanitation would makewhichofthefollowingmostlikelytooccur?
(A)An outbreak of Lyme disease.
(B)An outbreak of dengue hemorrhagicfever.
(C)An epidemic of typhoid.
(D)An epidemic of paralytic polio amonginfants.
(E)An epidemic of paralytic polio amongadolescence and adults.
从题目可知，该题的提问对象是：modern sanitation，因此我们需先回到原文定位。这里需要明确的一点是：原文的第11行和第17行的modern sanita-tion与hygiene是同一个概念。弄清了这一点之后便可发现，在第17行的因果关系词Thus后有这样一句话：the hy-giene that helped prevent...于是可轻松得出此题的答案正是句中提到的“typhoid epidemic”，(C)为正确。
2.According to the passage,the out-break of dengue hemorrhagic feverin the 1950's occurred for which ofthe following reasons?
(A)The mosquito Aedes aegypti wasnewly introduced into Asia.
(B)The mosquito Aedes aegypti becamemore numerous.
(C)The mosquito Aedes albopictus be-came infected with the dengue virus.
(D)Individuals who would normally ac-quire immunity to the dengue virusasinfantswerenotinfecteduntillaterinlife.
(E)Modern people began to visit andinhabitareasinwhichmosquitosliveand breed.
本题的提问对象是：dengue fever，其出现在原文的倒数第二句话中。定位之后不难发现，在dengue fever所在的句子中出现了一个因果关系短语b e-cause of，只要对原文中proliferate的意思与选项(B)中的numerous做一个同义替换，就能得出正确答案(B)。
3.It can be inferred from the passagethat Lyme disease has becomeprevalent in parts of the UnitedStates because of which of thefollowing?
(A)The inadvertent introduction of LymediseasebacteriatotheUnitedStates.
(B)The inability of modern sanitationmethods to eradicate Lyme diseasebacteria.
(C)A genetic mutation in Lyme diseasebacteria that makes them morevirulent.
(D)The spread of Lyme disease bacte-ria from infected human to nonin-fected humans.
(E)An increase in the number of hu-mans who encounter deer ticks.
本题提问的对象是文中所举的第二个例子：Lyme disease。答案可定位在第26行的due to之后，可见这个因果关系所引导的句子再一次成为了解题关键。根据句意对照选项，不难发现(E)选项最好地体现了Lyme disease在美国部分区域流行的原因。
综合官方文本题库中的几道考题，我们可以发现其中一半的提问是针对因果逻辑关系。因此，在拿到一篇GMAT文章时，我们可以先在文中表示因果关系的词上做一个标记，然后再根据题干内容扫描因果关系前后的几个句子，寻找信息。
表示因果关系的词或短语除了文中出现的due to、thus、because of，还有since、lead to、therefore、necessi-tate、result in/from、so that等等，大家在复习过程中可以自行归纳，并且一定要对这些表达方式形成阅读敏感，以节省答题时的思考时间，提高正确率。
上述就是小编为大家举例分析的GMAT阅读解题思路之因果关系法，不知道大家掌握了没有？好多阅读题的出题思路是一样的，只要考生能够掌握了这些GMAT阅读解题思路，以后遇到阅读题就不会犯愁了。
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