在同学们英语学习的过程当中，都会遇到一只拦路虎——长难句，托福考试也不例外。托福考试模拟了美国大学一年级或二年级公共课教材的难度，旨在衡量非英语国家的学生是否有足够的能力接受美国的教育。在托福阅读当中，长难句的考点是句子简化题。长难句在文章中被突出显示，要求考生选出一个最反映原句核心信息的选项。(Which of the sentences below best expresses the essential information in the highlighted sentence in the paragraph? Incorrect choices change the meaning in important ways or leave out essential information.)这类句子不仅单词难度高，而且句子结构非常复杂。要求考生有较好的语法背景或者语感良好。句子简化题的长难句最典型的情况就是对比对照，下面我们举例加以分析。

　　TPO1-Groundwater

　　原句：If the pores are large, the water in them will exist as d rops too heavy for surface tension to hold, and it will drain away; but if the pores are small enough, the water in them will exist as thin films, too light to overcome the force of surface tension holding them in place; then the water will be firmly held.

　　以分号为界，整个句子划分为两个层次。两句中间的But 是重要信号，明确的告诉我们前后文意相反。

　　参考译文：如果小孔很大，水会以水滴的形式存在，水滴过重表面张力无法支撑，从而水会流走;但是，如果小孔足够的小，水就会以薄膜的形式存在，这样就会很轻而不会克服表面张力，从而水会牢固的留下。

　　A. Surface tension is not strong enough to retain drops of water in rocks with large pores but it strong enough to hold on to thin films of water in rocks with small pores.

　　B. Water in rocks is held in place by large pores and drains away from small size pores through surface tension.

　　C. Small pores and large pores both interact with surface tension to determine whether a rock will hold water as heavy drops or as a thin film.

　　D. If the force of surface tension is too weak to hold water in place as heavy drops, the water will continue to be held firmly in place as a thin film when large pores exist.

　　下面我们来对比选项，A 选项完全重复了原句的含义，

　　A 为正确答案。

　　B 选项：如果岩石的孔足够大就会留下水，而小孔则会让水流走。乍一看选项出现了对比对照，但是仔细阅读后发现B 的内容和原句正好相反，这是托福典型迷惑选项：交叉匹配。

　　C 选项：大孔和小孔都会和表面张力发生作用，从而决定岩石中留下的水是水滴还是薄膜。明显的篡改，删除C 选项。

　　D 在大孔当中，如果表面张力太弱无法留住大水滴，水会继续以薄膜的形式牢牢地附着。D 选项已经把原句改的面目全非了。

　　在长难句分析中，对比对照句句的核心信息就是两者的不同点，只要抓住了核心特征，句子简化题就迎刃而解了。祝同学们考试顺利!