在托福阅读的课程中，常常被同学们问到的是如何提高阅读和做题效率的问题，因为大部分同学无法拿到阅读高分的核心原因是时间不够无法读全文章，直接做题又感觉患得患失地不知道选择的答案是否正确符合文章意思，这往往使得我们在备战阅读考试的效果大打折扣。

由于提高阅读速度是一个需要长期训练的过程，为了让同学们短期提高一些阅读分数和学习效果，我们来试试对比一些方法来高效的发现题目的切入点并且解决问题拿到分数。

我们来直接看题：

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.

<TPO17 Symbiotic Relationships>

1. Which of the following statements about commensalism can be inferredfrom paragraph 1?

○It excludes interactions betweenmore than two species.

○It makes it less likely for specieswithin a community to survive.

○Its significance to the organizationof biological communities is small.

○Its role in the structure ofbiological populations is a disruptive one.

解法1

初学者在看到这样题目的时候，会先把文章看完甚至翻译一遍，认为理解了自然就能选对答案。这是正确率最高最靠谱的做法，但最大的缺陷是考试时无法在短时间内理解文章并且做完题目。所以在阅读能力不是很强的时候，尽量不要使用看完理解再做题的方法。

解法2：

定位规律

• 题干关键词：commensalism

• 文中定位点：There are three main types ofsymbiotic relationships: parasitism, commensalism,and mutualism.有三种共生关系：寄生、共生、互利共栖。说的是题干关键词本身的内容，无法对应选项。

• 再往后读啊读啊读啊……理论上来说看到这里应该能得到答案了，但是……但是……看看选项？

○共生关系不包括超过两个物种之间的相互作用

○共生关系使得物种在生物团体中难以生存

○共生关系在生物群体中的重要性是小的

○共生关系在生物结构中的角色是引起混乱的

选哪个？！正确答案是哪个啊？

这里我们要学的是一个小套路，我们把文中内容和选项都理解后得到这样的一个逻辑：

文章：第一个和第三个在一个生物团体结构中是重要的；意思是，所有的有机体居住在一起并且在特定的区域相互作用。

推理模式：第一个（寄生）和第三个（互利共栖）在一个生物团体结构中是重要的→第二个（共生）是不重要的

☞所以选C

这个切入点你发现了吗？

但这样分析题目，对我们来说有什么实际的意义呢？同学们，这篇文章的核心就是希望大家能高效的发现题目的切入点并且解决问题。于是，对于这道题来说发现一个能够广泛使用的规律，比起选出正确答案更有意义：

让我们聊聊刚才在题目中的推理模式：第一个（寄生）和第三个（互利共栖）在一个生物团体结构中是重要的→第二个（共生）是不重要的。

这个推理模式我叫做反义推理（有些老师也叫做反向推理、取非，意思一致），是托福阅读推理题常用的推理模式，并且在细节题、否定事实信息题（NOTEXCEPT）和判断其他题型错误选项的时候经常使用，也是最常见的一种思维模式。反义推理的核心来自于归约（reduction），意思是当未知量与已知量看上去无法匹配的时候，在二者之间搭上一个桥梁来使得找答案变得更简单。

让我们来看看类似题目中用到反义推理的高效表现：

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 mighthave 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 wind blown silt.