句子插入题在托福阅读中几乎是每篇都有，并且位置还特别固定，永远倒数第二道。句子插入题的考察核心是考句子之间的衔接手法。而做题方法就是通过这些衔接手法找突破口，突破口对应法确定插入的位置。句子之间的衔接手法有以下几类：1. 代词衔接  2. 句子功能和作用（总述句，分述句，承上启下句）  3. 重复话题词衔接（即词或意群的同义重复） 4. 逻辑关系衔接（举例，因果等）。接下来以代词衔接和句子功能作用两个突破口为例教给大家托福阅读如何用突破口对应法来做题。

　　其中代词衔接是用的比较多也相对简单的方法，假如要插入的句子中有代词的话建议大家优先考虑代词衔接。但一定要注意代词的指代对象不能是文章或段落主题词。

　　接下来我们以一道题目为例讲解一下代词指代的应用。

　　TPO-43 The Origin of Petroleum

　　Paragraph 2 ■ Sampling on the continental shelves and along the base of the continental slopes has shown that fine muds beneath the seafloor contain up to 8 percent organic matter. ■ Two additional kinds of evidence support the hypothesis that petroleum is a product of the decomposition of organic matter: oil possesses optical properties known only in hydrocarbons derived from organic matter, and oil contains nitrogen and certain compounds believed to originate only in living matter. ■ A complex sequence of chemical reactions is involved in converting the original solid organic matter to oil and gas, and additional chemical changes may occur in the oil and gas even after they have formed. ■

　　13. Look at the four squares [■] that indicate where the following sentence could be added to the passage.

　　Because such muds are a major source of petroleum, scientists believe that petroleum originated as living organisms.

　　Where would the sentence best fit? Click on a square [■] to add the sentence to the passage.

　　首先，先读要插入的句子，发现有个代词such muds, 而muds并不是第二段的主题词，在第二段中也只出现了一次。于是，找muds的位置，在第二行的fine muds, 而要插入句子中的such muds就指代这个find muds啦，所以选B。

　　而通过句子功能作用来确立插入位置也是比较常见的方法，因为好多要插入的句子往往都是总述句，分述句或承上启下句。

　　接下来我们通过一道例题来看一下怎样通过句子功能作用来判断插入位置。

　　TPO-16 Trade and the Ancient Middle East

　　Paragraph 2 Reliance on trade had several important consequences. ■ Production was generally in the hands of skilled individual artisans doing piecework under the tutelage of a master who was also the shop owner. ■ In these shops differences of rank were blurred as artisans and masters labored side by side in the same modest establishment, were usually members of the same guild and religious sect, lived in the same neighborhoods, and often had assumed (or real) kinship relationships. ■ The worker was bound to the master by a mutual contract that either one could repudiate, and the relationship was conceptualized as one of partnership. ■

　　13. Look at the four squares [■] that indicate where the following sentence could be added to the passage.

　　For one thing, it created a demand for finished goods to be sold both locally and abroad.

　　Where would the sentence best fit?

　　在要插入的句子中有个For one thing, For one thing表示首先，说明要插入的句子一定是个分述句，并且还是分述的点，一般分述句都是在总述之后的，先总述再分述（在托福句子插入中很少有先分述再总结的）。而第2段首句Reliance on trade had several important consequences.明显是个总述句，先总述后分述，所以放首句之后，即选A，并且要插入的句子中还有个代词it, 通过句意，可看出这个it指代首句的Reliance on trade，那么选A无疑啦。

　　今天的讲解就到这里，通过比较常见的代词衔接来给大家展示一下句子插入题的做法。希望大家在今后的练习中习惯去通过找句子之间的衔接手法来做句子插入题，这样准确率会高很多。