一、从指代词入手

待插入的句子必然有很多成分，其中广泛存在的就是指代词，如：this, that, these, those, it, he, she, him, her, the, another, other以及定冠词the。指代词和定冠词必须在所指代的名词出现后才能使用。例如：当我们表达“我有一个苹果的时候”，我们要这样说：I have an apple而不是I have the apple。当我们要用两句话表达“我有一个苹果，这个苹果是绿色的”的时候，我们需要这样写：I have an apple. The apple is green. 而不是I have the apple. An apple is green. 指代词也是如此。根据这样的基本语法规则，我们可以这样总结：只要待插入的句子中出现了指代词或者定冠词，那么所指代名词在四个选项的位置中一定出现过(特殊情况除外)，我们应该把待插入的句子放在该名词在文中第一次提到的后面。然后，再根据句意判断是否通畅，逻辑是否符合即可。如：

We all know that many more people today are right-handed than left-handed. Can one trace this same pattern far back in prehistory? ■Much of the evidence about right-hand versus left-hand dominance comes from stencils and prints found in rock shelters in Australia and elsewhere, and in many Ice Age caves in France, Spain, and Tasmania. ■When a left hand has been stenciled, this implies that the artist was right-handed, and vice versa. ■Even though the paint was often sprayed on by mouth, one can assume that the dominant hand assisted inthe operation. One also has to make the assumption that hands were stenciled palm downward—a left hand stenciled palm upward might of course look as if it were a right hand. ■Of 158 stencils in the French cave of Gargas, 136 have been identified as left, and only 22 as right; right-handedness was therefore heavily predominant.

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

The stencils of hands found in these shelters and caves allow us to draw conclusions about which hand was dominant.

我们看到待插入的句子中有两个关键词：the stencils中的the以及these。但是由于A of B结构中的A若有the出现，the没有太大作用，文章前面不一定会出现相应名词，所以我们可以根据these shelters定位原文中shelters第一次在哪儿出现。通过scanning发现，shelters第一次出现是在第一个方框之后，所以初步确定答案是B。再次阅读上下文，逻辑和句意都挺合适。再次确认，答案是B。