除了词汇量较大以外，句子结构复杂也是托福阅读的障碍之一。面对难句，必须迅速把握其主干和重点，因为考试时涉及答案的主要是句子的主干和重点，对于句子简化题(sentence simplification)尤其如此。要把握难句的主干和重点，首先要弄清它们的类型。简而言之，托福中的难句主要包括下列类型：
1.定语(包含后置定语与定语从句)
2.同位语
3.并列结构
4.that引导的各种从句
5.插入结构
6.独立主格
7.倒装句
8.强调句
9.虚拟语气
•对于不同类型的难句，把握主干的方法也不一样。以倒装句为例，主要有下列情况：
1.方位副词放在句首
Herein lay the beginning of what ultimately turned from ignorance to denial of the value of nutritional therapies in medicine。
2.介词放在句首
Among the species of seabirds that use the windswept cliffs of the Atlantic coast of Canada in the summer to mate, lay eggs, and rear their young are common murres, Atlantic puffins, black-legged kittiwakes, and northern gannets。
3. 形容词放在句首
Implicit in it is an aesthetic principle as well: that the medium has certain qualities of beauty and expressiveness with which sculptors must bring own aesthetic sensibilities into harmony。
4.过去分词放在句首
Accustomed though we are to speaking of the films made before 1927 as “silent”， the film has never been, in the full sense of the word, silent。
5.现在分词放在句首
Missing until recently were fossils clearly intermediate, or transitional, between land mammals and cetaceans。
• 句子倒装的目的主要有两个：
一是被提前的部分被强调...