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。

托福考试托福备考托福分享托福机经