大家知道在托福考试中经常涉及到对于逻辑的考察，其中因果逻辑是托福阅读中常考的逻辑关系，利用因果逻辑能帮助我们迅速锁取定位，节约时间，下面我们看一下如何利用因果逻辑来快速定位解题。

　　审题

　　首先通过审题，利用因果逻辑词能确定是因果类事实信息题，比如下面的题干：

　　1. According to paragraph 6, why might the puzzling questions about the paintings never be answered?

　　2. According to paragraph 2, sculptors in the Italian Renaissance stopped using cannonballs in bronze statues of horses because

　　3. According to the passage, which of the following is one of the reasons that tunas are in constant motion?

　　4. According to paragraph 5, which of the following is a factor responsible for the greater air turbulence in urban environments?

　　通过why, because, reasons, response for这些词（短语），可以确定原文中会有相应的因果逻辑句（群）的表述。接下来我们只需要从原文中找出因句果逻辑表述的句（群），通过分析逻辑承接对象，匹配选项找出正确答案。

　　实战练习

　　例1．（tpo23p1q5）Paragraph 3

　　The burning of fuel, such as by cars, is not the only source of this increased heat. Two other factors contribute to the higher overall temperature in cities. The first is the heat capacity of the materials that constitute the city, which is typically dominated by concrete and asphalt. During the day, heat from the Sun can be conducted into these materials and stored—to be released at night. But in the countryside materials have a significantly lower heat capacity because a vegetative blanket prevents heat from easily flowing into and out of the ground. The second factor is that radiant heat coming into the city from the Sun is trapped in two ways: (1) by a continuing series of reflection among the numerous vertical surfaces that buildings present and (2) by the dust dome, the cloudlike layer of polluted air that most cities produce. Shortwave radiation from the Sun passes through the pollution dome more easily than outgoing longwave radiation does; the latter is absorbed by the gaseous pollutants of the dome and reradiated back to the urban surface.

　　5. According to paragraph 3, why do materials in the countryside have a lower heat capacity than materials in cities do?

　　○ The countryside in the Sun is the only important source of heat.

　　○ Construction materials in the city are not as good at keeping buildings warm as they are in the countryside.

　　○ In the countryside the solar heat that flows into the ground flows out again quickly.

　　○ Countryside vegetation prevents heat from being trapped in the ground.

　　· 分析

　　通过原文找出因果逻辑词我们发现有两处：

　　The first处“Two other factors contribute to the higher overall temperature in cities.”

　　第二处“But in the countryside materials have a significantly lower heat capacity because a vegetative blanket prevents heat from easily flowing into and out of the ground.”

　　细节题陷阱中有一种叫做偷换概念，需要考生们仔细审题，题干问的是“why do materials in the countryside have a lower heat capacity than materials in cities do?

　　The first处表达的是“the higher overall temperature in cities”的原因，显然不是我们要找的答案；

　　第二处说的是“in the countryside materials have a significantly lower heat capacity”，很明显答案在第二处，匹配选项答案是 D.

　　实战练习

　　例2.（OG: Lascaux Cave Painting）Paragraph 6

　　Perhaps so much time has passed that there will never be satisfactory answers to the cave images, but their mystique only adds to their importance. Certainly a great art exists, and by its existence reveals that ancient human beings were not without intelligence, skill, and sensitivity.

　　11. According to paragraph 6, why might the puzzling questions about the paintings never be answered?

　　○ Keeping the paintings a mystery will increase their importance.

　　○ The artists hid their tools with great intelligence and skill.

　　○ Too many years have gone by since the images were painted.

　　○ Answering the questions is not very important to scholars.

　　· 分析

　　这道细节题本身不难，但是出错率很高，很多学生选择A，为什么？因为C选项和原文“but their mystique only adds to their importance.”表达的意思一样。

　　细节题选的是符合题干的选项，也即是问什么答什么。比如我问张三有多高？张三说我很帅，张三确实帅但是不是我要的答案。细节题中很具有迷惑性的选项叫“答非所问”，同学们一定要细心，回到本题，题干问“why might the puzzling questions about the paintings never be answered?”，题干给的是结果，让我们找原因，扫读原文发现“Perhaps so much time has passed that there will never be satisfactory answers to the cave images，其中“that there will never be satisfactory answers to the cave images”表达的意思等于题干“the puzzling questions about the paintings never be answered”，很明显“so much time has passed”就是我们找的答案，确定正确答案选C。

　　实战练习

　　例3.(tpo7p1q7) Paragraph 4:

　　The time had come to formulate a hypothesis. The investigators theorized that about 20 million years ago, the Mediterranean was a broad seaway linked to the Atlantic by two narrow straits. Crustal movements closed the straits, and the landlocked Mediterranean began to evaporate. Increasing salinity caused by the evaporation resulted in the extermination of scores of invertebrate species. Only a few organisms especially tolerant of very salty conditions remained. As evaporation continued, the remaining brine (salt water) became so dense that the calcium sulfate of the hard layer was precipitated. In the central deeper part of the basin, the last of the brine evaporated to precipitate more soluble sodium chloride (salt). Later, under the weight of overlying sediments, this salt flowed plastically upward to form salt domes. Before this happened, however, the Mediterranean was a vast desert 3,000 meters deep. Then, about 5.5 million years ago came the deluge. As a result of crustal adjustments and faulting, the Strait of Gibraltar, where the Mediterranean now connects to the Atlantic, opened, and water cascaded spectacularly back into the Mediterranean. Turbulent waters tore into the hardened salt flats, broke them up, and ground them into the pebbles observed in the first sample taken by the Challenger. As the basin was refilled, normal marine organisms returned. Soon layer of oceanic ooze began to accumulate above the old hard layer.

　　7. According to paragraph 4, which of the following was responsible for the evaporation of the Mediterranean's waters?

　　○ the movements of earth's crust

　　○ the accumulation of sediment layers

　　○ changes in the water level of the Atlantic Ocean

　　○ changes in earth's temperature

　　· 分析

　　通过题干中 “responsible for”确定考察的是因果逻辑，定位到本段第三句话，但句子前后并没有找到明显的因果逻辑词，然后继续通读往下读，发现怎么读都觉得没有正确答案同时又浪费了很多时间。

　　在这里，给大家补充一个不常见的因果逻辑的另类表达，即and引导的两个句子也隐含因果逻辑关系。比如”He is too old and he can’t walk,”,仔细体会其中的意思“他太老了and不能行走”，蕴含的就是因果逻辑关系。

　　回到本题“Crustal movements closed the straits, and the landlocked Mediterranean began to evaporate. ”（因为地壳运动封闭了海峡，被陆地包围的地中海也开始蒸发。）如果大家能识别到这层关系，很明显A就是正确选项。

常见因果逻辑词

　　下面来总结一下托福阅读中常见的因果逻辑词，希望同学们能够熟记巧用。

　　显性：because(of), since, for, as, due to, owing to, In that, so(that), therefore, thus, hence, as a result, consequently...

　　隐性：cause, lead to, make，render, stimulate, spur, spark, push, motivate, prompt, be responsible for...