托福阅读重点题型推理题解读
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。
解答这里题目时要注意这些关键信息点：日期和数字、关键词： 表示多少的副词: many , some, much of, several , a few ,most …;情态动词：may, can , could…;表示过去的：used to be , was, were , at one time, previously ;表示不是唯一的： not only ,not exclusively等。
在此，我们在来看一道例题：
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 fluke3 and blowhole4 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.
首先我们来对题目的出题范围进行定位，题干的blowhole可以作为定位词汇，定位到原文的第四句话：“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.” 在这句话里交代了“unlike the casess of sea otters”，即与sea otters 不一样的是，whales 的陈述是：it is not easy to envision what the first whales looked like. 即，不容易看出第一头鲸长什么样子。而sea ottter 是和鲸鱼相反，所以选择A选项，即不难看出第一头sea otter 长什么样子。所以实际上，这种题目虽然叫做推理题，但是并不需要同学们在做题的时候推的过远，基本考察的还是对原文信息概括和总结的能力。
