不同的同学有不同的擅长点，就像面对托福阅读一样，如果要说托福阅读的十种题型，哪种最难，千人千答案，但如果我们从数据的角度来统计，就会发现，大多数的同学，对托福阅读的小结题和推断题，往往是要么因为时间，要么斟酌着不知道该选哪一项，从而大多数考生对这两种题型比较抗拒，下面我们就为大家分享一下如何用正逆向思维解决托福阅读推断题。
　　说到推断题，不要抗拒，更不要苦恼，虽然表面是推断题看着是云里雾里，但其实托福阅读没有你想像的那么难，因为托福作为标准化的考试，肯定会有一定的答题技巧，托福文章有很清晰的逻辑结构，每个自然段往往是按照TS (Topic Sentence) + SD (Supporting details)展开的，而文章多半是按Introduction + Aspects + Attitudes展开的。只有明白了文章的写作思路才能更好更快的做对题目，作者必定是按照一定的行文顺序编排段落的，如果画一个水平轴作为事件发展的顺序，推断题是让你从这个轴上的某一个点去推测，无非就两个方向，顺着轴发展的方向或者逆着轴发展的方向，也就是我们接下来要说的用正向和逆向思维去解决推断题。
　　OG上将推断题定义为检查考生对文章中强烈建议但绝不明说观点(strongly implied but not explicitly stated in the text)的理解程度，属于理解性题目，题目要求如下：
　　Paragraph 2 suggests which of the following about X?
　　Which of the following can be inferred from paragraph 2 about X?
　　According to paragraph 3, what do Y indicate about X?
　　According to paragraph 4, what does the author imply about X?
　　题干中有出现infer, imply, indicate或suggest这四个单词，我们就判定这个题目为推断题，那么推断题应该如何解答呢?
　　第一步，判断题型。我们拿到题目，看到上面四个单词中的任何一个，心中就想着这是推断题，推断题的做题宗旨是文章强烈暗示，要通过文章内容进行合理推断。
　　第二步，审清题干，原文定位。仔细阅读题干，弄清题干内容，推断方向，带着题干核心信息到文章中准确定位。
　　第三步，推测+判断。根据相关句进行正向或逆向的推理，最后择优而选，确定答案。
　　正向推断：和事实信息题做题方法一样，答案就是定位的句子的同义改写。
　　逆向推断：大致分为两种，一种是时间，第二种是两类事物的对比。
　　第一种，题干中往往会出现表示时间的信息，比如：after 1932, since early years of the 19th century. 例如TPO 20 Passage 1 Western Migration Q1:
　　Paragraph 1: The story of the westward movement of population in the US 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?
　　○They had limited their crop production to wheat, corn, tobacco and cotton.
　　○They were able to sell their produce at high prices
　　○They had not been successful in raising cattle.
　　○They did not operate in a national market economy.
　　题干中出现了两个信息，一个是western farmers, 一个是prior to 1815, 带着两条信息去文中定位，定位在第一段第四行，但是文章中没有提到1815年之前，只有1815年之后，答案其实很简单，只要把1815年之后的内容看懂了，并且在这个内容前面加not即可。举个简单的例子，“从现在起Jessica是个姑娘”，“请问你能推断出昨天Jessica怎么了么?”可能很多人想到“是不是Jessica做了变性手术?”，其实这就算过分推断了，答案就是Jessica昨天不是个姑娘。言归正题，文中说到，改善的交通使得越来越多的西部农民摆脱了自给自足的生活，并且进入了国家性的市场经济，那个时候货物的价格很多，所以向西迁移的速率也大幅增长。
　　第二种：两类事物的对比，往往文中会出现表示对比的关系词：by contrast, unlike, while, whereas, on the contrary, in comparison to, distinct from, different from等词。例如TPO 2中的The Origins of Cetaceans的第2题，让考生推测关于early sea otters的，回到原文中定位，会发现关键句中存在着一个unlike, 说不像sea otters, 想象一下早期鲸类比较困难(not easy=difficult)，那我们逆推一下，不就是说想象早期sea otters长什么样比较容易，正确答案中出现了not difficult, 所以这道题很简单。当然ETS不会一直都出这么简单的推断题，这里只是给大家一个答题的方向。
　　Paragraph 4: These ideas remain controversial. Proponents point to features such as the terraced "beaches" shown in one image, which could conceivably have been left behind as a lake or ocean evaporated and the shoreline receded. But detractors maintain that the terraces could also have been created by geological activity, perhaps related to the geologic forces that depressed the Northern Hemisphere far below the level of the south, in which case they have nothing whatever to do with Martian water. Furthermore, Mars Global Surveyor data released in 2003 seem to indicate that the Martian surface contains too few carbonate rock layers-layers containing compounds of carbon and oxygen-that should have been formed in abundance in an ancient ocean. Their absence supports the picture of a cold, dry Mars that never experienced the extended mild period required to form lakes and oceans. However, more recent data imply that at least some parts of the planet did in fact experience long periods in the past during which liquid water existed on the surface.
　　10. According to paragraph 4, what do the 2003 Global Surveyor data suggest about Mars?
　　○Ancient oceans on Mars contained only small amounts of carbon.
　　○The climate of Mars may not have been suitable for the formation of large bodies of water.
　　○Liquid water may have existed on some parts of Mars' surface for long periods of time.
　　○The ancient oceans that formed on Mars dried up during periods of cold, dry weather.
　　解析：根据关键词我们定位到文段的中间部分：Mars Global Surveyor data released in 2003 seem to indicate that the Martian surface contains too few carbonate rock layers-layers containing compounds of carbon and oxygen-that should have been formed in abundance in an ancient ocean.这道题可以当做事实信息题去做，但注意不是原文的简单重复，suggest 是原文中indicate的同义转换，我们只要找到what就好了，原文that后面是重点，出现了too few, should have,
　　情感态度推测一下，持否定态度，也就说说形成 an ancient ocean不太可能，我们看选项，A中说Ancient oceans on Mars contained only small amounts of carbon.主客体与原文矛盾，排除;B选项 The climate of Mars may not have been suitable for the formation of large bodies of water.说不适合形成大量的水，持否定态度，符合原文，保留;C选项Liquid water may have existed on some parts of Mars' surface for long periods of time.相关句中未提及，排除;D选项The ancient oceans that formed on Mars dried up during periods of cold, dry weather. 说的是ancient oceans没有，而不是原来有后来干涸了，与原文不符，排除，所以正确答案为B。
　　面对托福阅读推断题，不论是正推还是逆推，关键是大家要保持冷静的头脑，从事件发展的时间轴或者事件水平轴上进行原因的推断，找某个突破点，依据原文的内容，找出相应的根据，那么你的托福阅读推断题的正确率，一定会很好的提升，不信，你现在就可以实践一下。