托福阅读中推断题
推论题(Inference)：文章中有些论点/观点没有明确阐述，但却强烈暗示出来了。例如，文章论述的结果引出了，推论题就可能就造成结果的起因提问。如果文中有比较，推论题就可能问做比较的基础是什么。如果文中有对某一新现象的明确阐述，推论题就可能要求推论旧现象的特征。推论题虽然是传统题型，但难度很大，需要考生花大功夫准备。

推理题的标志是在题干中出现infer/imply/suggest/indicate/most likely这样的词汇，它和细节题属于同源题目，都需要定位并且根据文中信息来选择答案。与细节题不同的是，推理题在找到原文中定位点之后考察的是学生对于文中信息的总结概括，或者反向推理的能力。

推理题的两大分类：有共性的推理题和无共性的推理题。这里所谓的有共性推理题就是说题干中有和原文内容相同的关键词(也叫线索)。根据关键词回原文定位，然后进行推理。一般来说，大多数的推理题都属于这类题目。对于无共性的推理题，也就是题干中无线索，一般使用排除法，即根据各个选项的关键词回原文定位，通过排除法得出正确答案。返回原文找信息点，采用排除法是解决这两类题型解决的共同策略。
推理题大概有三个解题思路：一般对比推理、时间对比推理、集合概念推理。一般对比推理：根据两个事情的对比特征，问其中一个事物的特征，只要将与之形成对比的另外一个事情的特征否定掉就可以。时间对比推理：在这种推理中，一般有两个形成对比的时间段，它们所具有的特征一般相反。当题干问一个时间段的特征时，只要将与之相反的时间段的特征否定掉就可以了。集合概念推理：一个大的集合的两个方面形成对比，两者之间存在着互补性关系，也就是一个的增加意味着另一个的减少。反之，相同。
在这里我们先来看一个例子：
Passage：…The nineteenth century brought with it a burst of new discoveries and inventions that revolutionized the candle industry and made lighting available to all.In the early-to-mid-nineteenth century，a process was developed to refine tallow(fat from animals)with alkali and sulfuric acid.The result was a product called stearin.Stearin is harder and burns longer than unrefined tallow.This breakthrough meant that it was possible to make tallow candles that would not produce the usual smoke and rancid odor.Stearins were also derived from palm oils，so vegetable waxes as well as animal fats could be used to make candles...
Which of the following can be inferred from paragraph 1 about candles before the nineteenth century?
a.They did not smoke when they were burned.
b.They produced a pleasant odor as they burned.
c.They were not available to all.
d.They contained sulfuric acid.
正确答案是C.这一段的第一句就告诉我们：19世纪的一些新发明和发现也对蜡烛工业产生了一次巨大的革命，这次革命使得所有的人都使用上了照明。从这句话中我们可以得到两层信息：19世纪蜡烛工业有了一次革命性的变化;在没有这次变革之前，也就是在19世纪以前，照明并不是所有人都能使用的。因为作者在谈论的是蜡烛的变革，所以这里所说的“lighting照明”一定是与蜡烛有关的照明，其实也就是告诉我们19世纪以前并不是所有人都能够使用到蜡烛带来的照明，这一推论出的信息正好与选项C吻合。文章第一句同时也是一个时间的分水岭，告诉我们19世纪蜡烛工业的变革是怎么样的。“在19世纪早期到中期，蜡烛处理工艺使用alkali和sulfuric acid来提炼tallow，提炼后的产品就是stearin，stearin比未经提炼的tallow坚硬而且燃烧得更久。这一巨大的变化意味着制造出不产生烟和rancid味道的蜡烛是可能的。”在这里的一个关键词是rancid，意思是(油脂食物，其味道、气味)不新鲜的;腐臭的;正好与选项b的pleasant odor相反。19世纪前的蜡烛产生usualsmoke(经常有烟)，这与选项a相反。Sulfuric acid是19世纪用来处理fallow的材料，在19世纪以前是没有使用的，这与选项d相反。

托福阅读推断题的三种解题方式
推断题Inference Question，又叫推理题，是许多同学最烦恼的阅读题型。往往阅读已达25分以上的同学，最后的几道错题中就有推断题的身影。曾遇到一个分数已经29的高分学员，二刷托福的最后阶段，还是每每在推断题上栽跟头。
原因呢，就在于推断题逻辑的“模糊”——比起大部分题型，比如细节题简单粗暴、非黑即白的逻辑，推断题的态度要显得暧昧许多。但首先我们要确定的是，虽然很难在原文中找到直接的同义改写，但文中一定会有依据。一旦依据不足，那做的就不是推断题，而是“脑补题“了。问我们：“What can we infer about XXX”，实际上是问“作者对XXX有什么潜台词?”
潜台词里套路多，所以我们首先把题目分为两类。一类是(1)“题干定位“型，一类可以叫作(2)“选项定位型“。读完题干就可以区分。举个简单的例子：
现在城市中养猫的人群正在兴起，逐渐改变了以往狗多猫少的情况。其中原因有很多，首先，比起养狗，养猫更加方便。猫咪几乎没有体味，不需要遛，也不需要经常洗澡：猫会自己“洗澡”。与狗不同，它们的唾液有很强的清洁力。此外，猫比狗需求的陪伴更少，这很适合生活忙碌的白领人群。现代宠物行业培养了许多适宜家养的猫咪品种。比如美国短毛猫，脾气较为温顺，尤其是银虎斑，性格乖巧，适合作为家养宠物。
根据这段原文出两道推断题。(1)关于美国短毛猫，我们可以推断出什么结论?(2)关于养猫，我们可以推断出什么结论?那么第一题就是“题干定位题”，因为“美国短毛猫”可以确定定位区间——原文的最后一句话。而第二题，我们却显然无法根据题干来定位，因为整段文字都是讲养猫的。所以第二题我们采取的策略是根据选项去定位。我们可以叫它“选项定位型”。
区分了两种类型，就可以分别看看它们的套路了!
定位型的推断题详解
今天我们要详细讲解的是题干定位型的推断题。以下是一些用得上的推理逻辑。
1.反向推理
要有信心的是：只要题干中的关键词是可以定位的，这道题就肯定不难，肯定可以拿下。我们要做的就是紧扣定位区间，从几句话中确定依据，再回头看选项。很快就可以知道哪几个选项的依据不足。我们还是根据上面这个养猫的例子来出几道题，考考大家的逻辑。
1.关于动物的唾液，我们能推断出什么结论?
A.猫的唾液比人类的沐浴液更有清洁力。
B.狗的唾液没有清洁力。
C.动物的唾液都有清洁力。
D.因为猫的唾液可以自我清洁，所以猫的一生不需要洗澡。
这道题拿到手，当然是用“唾液“作为关键词去定位。找到定位区间：“猫咪并不需要遛，也不需要经常洗澡：猫会自己“洗澡”。与狗不同，它们的唾液有很强的清洁力。“依据仅有这两句话，其中没有提到“人类的沐浴液”，因此排除A;“猫不需要经常洗澡”和D中的“一生不需要洗澡”矛盾，排除D;C显然不对，因此选择B。
B这个选项，我们叫做反向推理，由“与狗不同，……”这句话推出。这个逻辑非常常见。现在来看一看TPO中的练习题：
It should be obvious that cetaceans–whales,porpoises,and dolphins–are mammals.They breathe through lungs,not through gills,and give birth to live young.Their streamlined bodies,the absence of hind legs,and the presence of a fluke and blowhole cannot disguise their affinities with land-dwelling mammals.However,unlike the cases of sea otters and pinnipeds(seals,sea lions,and walruses,whose limbs are functional both on land and at sea),it is not easy to envision what the first whales looked like.Extinct but already fully marine cetaceans are known from the fossil record.How was the gap between a walking mammal and a swimming whale bridged?Missing until recently were fossils clearly intermediate,or transitional,between land mammals and cetaceans.
Which of the following can be inferred from paragraph 1 about early sea otters?
A.It is not difficult to imagine what they looked like.
B.There were great numbers of them.
C.They lived in the sea only.
D.They did not leave many fossil remains.
这道题是非常经典的题干定位、反向推理。题干中的sea otter,定位到的区间为unlike the cases of sea otters and pinnipeds(seals,sea lions,and walruses,whose limbs are functional both on land and at sea),it is not easy to envision what the first whales looked like.逻辑和上面那道例题非常相似，根据unlike推出sea otter情况与cetacean相反，因此选A。
还有一种更为隐晦的反向推理。比如，托福出分了，妈妈对你说：你和小明、小红都是一个班的，你看看小明这次考得特别好，小红也考得不错!请问根据妈妈的话可以推断出什么?当然是妈妈的潜台词：“你”没有考好。这件事妈妈没有明说，但仍然是反向推理出来的。
那就让我们把这种题目拿下，考出个超级好的成绩，让妈妈无话可说：
A symbiotic relationship is an interaction between two or more species in which one species lives in or on another species.There are three main types of symbiotic relationships:parasitism,commensalism,and mutualism.The first and the third can be key factors in the structure of a biological community;that is,all the populations of organisms living together and potentially interacting in a particular area.
Which of the following statements about commensalism can be inferred from paragraph 1?
A.It excludes interactions between more than two species.
B.It makes it less likely for species within a community,to survive.
C.Its significance to the organization of biological communities is small.
D.Its role in the structure of biological populations is a disruptive one.
根据题干的commensalism,找到定位区间“There are three main types of symbiotic relationships:parasitism,commensalism,and mutualism.The first and the third can be key factors in the structure of a biological community”。第一句话罗列了三种关系，第二句话强调了第一种和第三种是key factor，那么没有提到的第二种——也就是题干所问的这一种，就是与之相反的不是key factor。答案呼之欲出：就是C,its significance is small.
再来一题更难的：
With question such as these clearly before them,the scientists aboard the Glomar Challenger processed to the Mediterranean to search for the answers.On August 23,1970,they recovered a sample.The sample consisted of pebbles of hardened sediment that had once been soft,deep-sea mud,as well as granules of gypsum and fragments of volcanic rock.Not a single pebble was found that might have indicated that the pebbles came from the nearby continent.In the days following,samples of solid gypsum were repeatedly brought on deck as drilling operations penetrated the seafloor.Furthermore,the gypsum was found to possess peculiarities of composition and structure that suggested it had formed on desert flats.Sediment above and below the gypsum layer contained tiny marine fossils,indicating open-ocean conditions.As they drilled into the central and deepest part of the Mediterranean basin,the scientists took solid,shiny,crystalline salt from the core barrel.Interbedded with the salt were thin layers of what appeared to be windblown silt.
Which of the following can be inferred from paragraph 3 about the solid gypsum layer?
A.It did not contain any marine fossil.
B.It had formed in open-ocean conditions.
C.It had once been soft,deep-sea mud.
D.It contained sediment from nearby deserts.
这题拿到手，还是找定位区间：“the gypsum was found to possess peculiarities of composition and structure that suggested it had formed on desert flats.Sediment above and below the gypsum layer contained tiny marine fossils,indicating open-ocean conditions.”第一句话说gypsum的内在结构说明它是在沙漠形成的;第二句话讲了gypsum上下两层的情况：富含marine fossils。从第二句话中，我们倾向于推出中间的gypsum曾并没有marine fossils，逻辑和上题一样。第一句话给了我们佐证：gypsum本身应当从沙漠来，当然没有海洋沉淀。答案：A。
反向推理的逻辑大致如此。其中还有一种较为特殊的“时间推理”，我们也可以看一看。
2.时间推理
时间推理的逻辑非常简单。大致就是：小明在2017年去了美国读大学——可以推出2017年以前小明没有去美国读大学。通过时间先后来反推，其实也属于反向推理中的一种。一道简单的TPO：
The story of the westward movement of population in the United States is,in the main,the story of the expansion of American agriculture—of the development of new areas for the raising of livestock and the cultivation of wheat,corn,tobacco,and cotton.After 1815 improved transportation enabled more and more western farmers to escape a self-sufficient way of life and enter a national market economy.During periods when commodity prices were high,the rate of westward migration increased spectacularly.
What can be inferred from paragraph 1 about western farmers prior to 1815?
A.They had limited their crop production to wheat,corn,tobacco,and cotton.
B.They were able to sell their productat high prices.
C.They had not been successful in raising cattle.
D.They did not operate in a national market economy.
答案选C。你选对了吗?
再来看一看时间推理更进一步的题会出成什么样：
This was before the steam locomotive,and canal building was at its height.The companies building the canals to transport coal needed surveyors to help them find the coal deposits worth mining as well as to determine the best courses for the canals.This job gave Smith an opportunity to study the fresh rock outcrops created by the newly dug canal.He later worked on similar jobs across the length and breadth of England all the while studying the newly revealed strata and collecting all the fossils he could find.Smith used mail coaches to travel as much as 10000 miles per year.In 1815 he published the first modern geological map“A Map of the Strata of England and Wales with a Part of Scotland”,map so meticulously researched that it can still be used today.
Which of the following can be inferred from paragraph 2 about canal building?
A.Canals were built primarily in the south of England rather than in other regions.
B.Canal building decreased after the steam locomotive was invented.
C.Canal building made it difficult to study rock strata which often became damaged in the process.
D.Canal builders hired surveyors like Smith to examine exposed rock strata.
这道题目跪了无数人。其实这题看似信息杂乱，但题目中的canal building是可以定位的：文中的前3句话。第一句话就是题眼所在：在steam locomotive出现之前，canal building was at its height。你是否理解了at its height?它表示“达到了顶峰“。所以简单地画一个图，是这样的：
所以选B，毫无疑问。A信息不足，而C和D都和原文有不同程度的出入。