首先，因果关系词，其实有两类，一个是表示原因的：as、since、thanks to、as result of、because of、owing to、result from、due to、on account of、by virtue of、in that、attribute to;另一个是表示结果的：as a consequence、thus、hence、so、as a result、result in、contribute to、lead to、cause、breed、trigger

　　我们来分析一下因果关系词在托福阅读推断题解答中是怎么运用的。

　　Paragraph 4: So, in another set of experiments, Kramer put identical food boxes around the cage, with food in only one of the boxes. The boxes were stationary, and the one containing food was always at the same point of the compass. However, its position with respect to the surroundings could be changed by revolving either the inner cage containing the birds or the outer walls, which served as the background. As long as the birds could see the Sun, no matter how their surroundings were altered, they went directly to the correct food box. Whether the box appeared in front of the right wall or the left wall, they showed no signs of confusion. On overcast days, however, the birds were disoriented and had trouble locating their food box.

　　Which of the following can be inferred from paragraph 4 about Kramer’s reason for filling one food box and leaving the rest empty?

　　A He believed the birds would eat food from only one box.

　　B He wanted to see whether the Sun alone controlled the birds' ability to navigate toward the box with food.

　　C He thought that if all the boxes contained food, this would distract the birds from following their migratory route.

　　D He needed to test whether the birds preferred having the food at any particular point of the compass.

　　首先，我们来明确一下推断的定义(infer, imply, indicate)，纵使它是推断题，也不是意味着这题是主观臆断，臆想或是联想得出的。这道题也是要通过提取题干中的关键词到文章中的明确位置，然后文中没有平铺直叙地告诉你答案，需要我们根据一些线索找到答案。

　　接下来我们来看一下这道题，题干中出现Kramer, filling one food box and leaving the rest empty定位在第四段第一句：with food in only one of the boxes，而解开这道题的重点就在于：reason。我们看到第一句话一开始说到，so, in another set of experiments，很明显，答案并不在这一段，而是上一段的最后。所以答案是B。