托福阅读的背景内容涉及人文历史、生命科学和天文地质等等，各个学科的专有词汇让同学们背得头疼。有上知天文下知地理的学霸直接靠自己的背景知识就能做对题目，但是托福阅读出题的本意并不是想考查学生学科知识的丰富程度，而是靠基础词汇（高四六托福核心）和逻辑来读懂文章想要表达的内容。其中，与逻辑（包括因果、比较、条件、转折让步等）相关的句子往往是文章的重点，而且比较好拿分，各个水平阶段的学生都应该掌握。
结合多位同学的错题情况，本文分析下应如何结合比较逻辑来解题：
首先，注意原文/题目/选项中出现的比较逻辑词：
表“相同”
1.same、similar、equal、alike、identical（可靠“identical twins同卵双胞胎”来背诵这个单词）
2.as ... as、just as
3.前缀homo-
表“不同”
1.比较级-er...than、高级the most/-est
2.rather than(而不是)
3.whereas、while、although/but、unlike、not as … as
其次，定位好后将原句与选项进行同义转换
表“相同”的情况：
TPO 48 R2 Determining Dinosaur Diet
Animals such as house cats and dogs have large, stabbing canine teeth at the front of the mouth and smaller, equally sharpteeth farther back in their jaws. Many of these animals are also armed with sharp claws. The advantage of teeth and claws as predatory tools is obvious. Now consider animals like cows, horses, rabbits, and mice. These animals have flat teeth at the back of the jaw that are analogous to and have the same function as grindstones. Unlike the meat-slicing and stabbing teeth of carnivores, the teeth of these animals grind and shred plant material before digestion.
2.According to paragraph 2, which of the following is true of the teeth of carnivores?
A. Carnivores’ teeth for grinding and shredding are located in the front of their jaws
B.Carnivore teeth are designed to break down food thoroughly before digestion
C.Carnivores have teeth at the back of their jaws that are as sharp astheir front teeth
D.Carnivores have both sharp teeth for slicing meat and flat teeth for grinding meat
分析：原文说某些动物嘴里前面大的牙齿和后面小的牙齿一样锋利（equally sharp），同义替换C选项“…back … as sharp as …front…”。
TPO 41 R3 Trade And Early State Formation
In the 1970s, a number of archaeologists gave trade a primary role in the rise of ancient states. British archaeologist Colin Renfrew attributed the dramatic flowering of the Minoan civilization on Crete and through the Aegean to intensified trading contacts and to the impact of olive and vine cultivation on local communities. As agricultural economies became more diversified and local food supplies could be purchased both locally and over longer distances, a far-reaching economic interdependence resulted. Eventually, this led to redistribution systems for luxuries and basic commodities, systems that were organized and controlled by Minoan rulers from their palaces. As time went on, the self-sufficiency of communities was replaced by mutual dependence. Interest in long--distance trade brought aboutsome cultural homogeneity from trade and gift exchange, and perhaps even led to piracy. Thus, intensified trade and interaction, and the flowering of specialist crafts, in a complex process of positive feedback, led to much more complex societies based on palaces, which were the economic hubs of a new Minoan civilization.
5.According to paragraph 2, Renfrew believed that one effect of long-distance tradein the Aegean was
A.a greater effort to control piracy
B.greater cultural similaritythroughout the region
C.a decline in local olive production
D.a decline in the use of luxuries for gift exchanges

分析：用“effect of long-distance trade”定位到原句后，“cultural homo-” 同义转换成选项B里的“cultural similarity”（都表“文化相同“）。
表“不同”的情况：
TPO 44 R3 Seagrasses
Seagrass beds under the influence of strong currents tend to have many of the lighter particles, including seagrass debris, moved out, whereas beds in weak current areas accumulate lighter detrital material.
Question: Which of the sentences below best expresses the essential information in the highlighted sentence in the passage? Incorrect choices change the meaning in important ways or leave out essential information
A.Light particles and debris collect in some seagrass beds, but are washed out of those affected by strong currents.
B.Seagrass beds under the influence of strong currents tend to accumulate many of the lighter particles from other beds.
C.The strength of the currents determines how quickly accumulated seagrass debris is moved out of the beds.
D.Seagrass debris and other light particles are often moved from areas of strong currents to areas of weak currents.
分析：对于部分词汇不够完善的同学来说，这个原句有一定难度；但原句出现whereas，同学们要理解成拿“strong currents”和“weak currents”进行比较。只有选项A用“虽然。。。但是。。。”来表达出比较的意思，所以即使在原句没有完全读懂的基础上，也应该选A。
长难句：Immediately adjacent to the timberline, the tundra consists of a fairly complete cover of low-lying shrubs, herbs, and grasses, while higher up the number and diversity of species decrease until there is much bare ground with occasional mosses and lichens and some prostrate cushion plants.
分析：这个句子难点在于和植物相关的专业词汇非常多，逐字逐句翻译非常困难而且浪费时间。此句出现while，而且后接“在更高的地方（higher up），物种的数量和多样性会下降”，所以应该根据对比逻辑合理猜测：在海拔低的地方，植物的多样性和数量都会上升。特别是在题目没有对此句进行提问的情况下，靠逻辑读句更能加快读句速度。