托福阅读难在哪里?对于很多同学来说,词汇是硬伤。一句话十个单词，七八个没看懂，那说明得好好背单词了。还有一部分同学是词汇都认识，整句话却愣是没看懂。问题出在哪里呢?我们知道托福阅读句子大都很长，一句话占考试页面三四行都很常见。为什么阅读偏爱长句呢?我们知道托福考试是没有单独对语法这一项进行测试的。而阅读文章当中的长难句就体现了对学生语法基础的检测。想要让句子变长，主要方法之一就是通过从句。阅读文章中，出现频率高的当属that所引导的定语从句，同位语从句和宾语从句。下面我们来学习一下这些从句的特点，希望对大家备考托福阅读有所帮助。
　　名词 that
　　that引导定语从句或同位语从句。
　　首先我们来区分一下定语从句和同位语从句：
　　that引导的定语从句：定语即限定，修饰；从句部分缺主语（更常见）或宾语。如I like the idea that can make him happy.我们可以发现谓语can make前缺主语，所以idea充当主语，译成：我喜欢这个可以让他开心的主意。
　　that引导的同位语从句：同位即同等位置，从句具体说明前面名词的内容；从句不缺成分，。如I like the idea that we may have a party.从句当中成分完整；从句具体说明idea的内容是什么。意思是：我喜欢这个主意（主意的内容是我们要开party）。
　　练习：
　　People in the United States in the nineteenth century were haunted by the prospect that changes in the nation's economy would bring social chaos．
　　主语：people; 介词短语in the United States in the nineteenth century是修饰成分，表明地点，时间；were haunted是整个句子的谓语；接下来我们看到名词prospect 后面有that, that从句当中成分完整（主：changes in the nation's economy；谓语：would bring；宾语：social chaos）。所以that 在这里引导同位语从句。
　　句子主干：People were haunted by the prospect.
　　练习：
　　The strikingly new forms of architecture that appeared in the late nineteenth and twentieth centuries were built to meet the needs of industry.
　　我们看到主语The strikingly new forms of architecture后面的that，再看到that 后面的appeared缺主语，可以判断是that引导定语从句，先行词充当主语。定语从句到第二个动词were built前结束。所以这句话的谓语是were built.
　　句子主干：The strikingly new forms of architecture were built to meet the needs of industry.
　　动词 that
　　that引导宾语从句；从句不缺成分。
　　如：Mary believes that she will pass the exam.
　　Mary相信的内容用一个完整的句子来表达.
　　练习：
　　The structure of the backbone shows that Ambulocetus swam like modern whales by moving the rear portion of its body up and down.
　　很明显，主语：The structure of the backbone，整个句子的谓语：show。动词show后面出现that,所以我们知道that在这里引导宾语从句，整个从句就是The structure of the backbone所show的内容。