一、推理题的标志
　　推理题的题干中一般含有infer， imply， most likely， least likely， probably等词，分为有共性的推理题和无共性的推理题两大类。
　　二、推理题的做法
　　对于无共性的推理题，也就是题干中无线索的，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。
　　对于有共性的推理题，也就是题干中有线索的，可以先圈定题干中的关键词，根据关键词回原文定位，然后进行推理。推理题主要有下列思路：
　　1.一般对比推理
　　ETS设计推理题的手段不多，根据两个事物的对比特征出题是其中之一。问其中一个事物的特征时，只要将与之形成对比的另一个事物的特征否定掉就可以了。例如：
　　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 fluke and blowhole 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.
　　2. Which of the following can be inferred from paragraph 1 about early sea otters?
　　?It is not difficult to imagine what they looked like.
　　?There were great numbers of them.
　　?They lived in the sea only.
　　?They did not leave many fossil remains.
　　根据关键词sea otters定位第四句：However， unlike the cases of sea otters and pinnipeds…，由原文的unlike可知sea otters和pinnipeds两种动物与whales形成对比，而且很难想象原始的whales的样子;根据“一般对比推理”思路， 可以推出“原始的sea otters的样子不难想象”。第一个选项表达了此意，为正确答案。
　　2.时间对比推理
　　这种思路常被考到。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。
　　例一：
　　Basic to any understanding of Canada in the 20 years after the Second World War is the country’s impressive population growth….
　　…It appeared that Canada was once more falling in step with the trend toward smaller families that had occurred all through the Western world since the time of the Industrial Revolution.
　　…
　　It can be inferred from the passage that before the Industrial Revolution
　　(A)families were larger.
　　(B)population statistics were unreliable.
　　(C)the population grew steadily.
　　(D)economic conditions were bad.
　　工业革命之后与工业革命之前两个时间形成对比。既然工业革命之后西方世界的家庭变小了，那么工业革命之前的家庭一定比较大。因此(A)为正确答案。
　　例二：
　　Accustomed though we are to speaking of the films made before 1927 as “silent”， the film has never been， in the full sense of the word， silent. From the very beginning， music was regarded as an indispensable accompaniment; when the Lumiere films were shown at the first public film exhibition in the United States in February 1896， they were accompanied by piano improvisations on popular tunes. At first， the music played bore no special relationship to the films; an accompaniment of any kind was sufficient. Within a very short time， however， the incongruity of playing lively music to a solemn film became apparent， and film pianists began to take some care in matching their pieces to the mood of the film.
　　What can be inferred from the passage about the majority of films made after 1927?
　　(A) They were truly “silent.”
　　(B) They were accompanied by symphonic orchestras.
　　(C) They incorporated the sound of the actors’ voices.
　　(D) They corresponded to specific musical compositions.
　　1927年前后形成对比。既然1927年以前的电影只有音乐而没有配音，那么1927年之后的电影一定有。所以(C)为正确答案。
　　例三：
　　“…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?
　　?They did not smoke when they were burned.
　　?They produced a pleasant odor as they burned.
　　?They were not available to all.
　　?They contained sulfuric acid.
　　问题：关于19世纪以前的蜡烛，从第一段可以推出下列哪一点?
　　这道题的题干中有“19世纪以前”这一时间，由此可见它属于“时间对比推理”思路。原文首句指出：“…19世纪带来了大量新发现和发明，使蜡烛业发生了革命性的变化，所有人都能用蜡烛照明。” 根据“时间对比推理”思路，由于19世纪以前的情况与19世纪形成对比，而19世纪所有人能用蜡烛照明，那么在19世纪之前，并非所有人都能用上蜡烛。第三个选项 “They were not available to all”表达了这一意思，为正确答案。
　　2.集合概念推理
　　集合概念推理也可以称之为百分比推断，它指的是在一个集合中，包含两个相对的方面，共同构成一个大的集合。一方所占的比例减少意味着另一方所占比例的增加;反之，一方所占的比例增加意味着另一方所占比例的减少。根据这一思路，可以由集合中一方的数量变化推断另一方的消减。
　　例一：
　　A folk culture is small， isolated， cohesive， conservative， nearly self-sufficient group that is homogeneous in custom and race， with a strong family or clan structure and highly developed rituals. …Unaltered folk cultures no longer exist in industrialized countries such as the United States and Canada….
　　By contrast， a popular culture is a large heterogeneous group， often highly individualistic and constantly changing.
　　22.What does the author imply about the United States and Canada?
　　(A) They value folk cultures.
　　(B) They have no social classes.
　　(C) They have popular cultures.
　　(D) They do not value individualism.
　　原文谈到folk culture 和popular culture两种文化，它们之间形成对比。既然美国和加拿大不再存在folk culture，那么它们就有popular culture。因此(C)为正确答案。
　　例二：
　　Both the number and the percentage of people in the United States involved in nonagricultural pursuits expanded rapidly during the half century following the civil war， with some of the most dramatic increases occurring in the domains of transportation， manufacturing， and trade and distribution.
　　What can be inferred from the passage about the agricultural sector of the economy after the Civil War?
　　(A) New technological developments had little effect on farmers.
　　(B) The percentage of the total population working in agriculture declined.
　　(C) Many farms destroyed in the war were rebuilt after the war.
　　(D) Farmers achieved new prosperity because of better rural transportation.
　　文中指出：非农业人口的数量和比例都增加了。由此可知农业人口的数量和比例下降了。所以(B)为正确答案。