Car manufacturers and governments have been eagerly seeking a replacement for the automobile's main source of power, the internal-combustion engine. By far the most promising alternative source of energy for cars is the hydrogen-based fuel-cell engine, which uses hydrogen to create electricity that, in turn, powers the car. Fuel-cell engines have several advantages over internal-combustion engines and will probably soon replace them.（开头段）
One of the main problems with the internal-combustion engine is that it relies on petroleum, either in the form of gasoline or diesel fuel. Petroleum is a finite resource; someday, we will run out of oil. The hydrogen needed for fuel-cell engines cannot easily be depleted. Hydrogen can be derived from various plentiful sources, including natural gas and even water. The fact that fuel-cell engines utilize easily available, renewable resources makes them particularly attractive.（主体段1）
Fuel-cell-engines have several advantages over internal-combustion engines, 然后三个主体段落分别展开说明。
以上列举了这个阅读文章的开头段和主体段1, 笔者在平时的教学中发现学生在看完阅读文章后，并没有真正理解文章的行文风格：fuel-cell engine和internal-combustion engine在全文中进行对比论证，正是由于没有理解这层关系，学生就按照惯例认为主体段第一句话是文章的中心，误认为中心句是：One of the main problems with the internal-combustion engine is that it relies on petroleum, either in the form of gasoline or diesel fuel.
然后学生就开始记听力笔记，大致内容是：be not easily available, store in an extremely surrounding, minus 253 degrees centigrade…
听力内容与阅读内容没有相对应的点，那么前后的逻辑性就很混乱了。问题就出在考生弄错了这篇阅读文章真正要谈的内容，这篇文章真正的主题是fuel-cell engine, 而不是internal-combustion engine。
这个段落真正的主题句应该是：The hydrogen needed for fuel-cell engines cannot easily be depleted, 这样根据刚才的听力笔记的关键词来看阅读和听力材料的具体内容才是一一对应的。
可见，在拿到一篇阅读文章时，考生们一定要明白全文是对比论证，还是举例论证。若是对比论证（如：上文中TPO 9的例子），要准确地找到研究内容；若是举例论证，文章的总分结构要明确，下面以TPO 5示范。
One theory holds that the Chaco structures were purely residential, with each housing hundreds of people. Supporters of this theory have interpreted Chaco great houses as earlier versions of the architecture seen in more recent Southwest societies. In particular, the Chaco houses appear strikingly similar to the large, well-known "apartment buildings" at Taos, New Mexico, in which many people have been living for centuries.（阅读材料）
这篇阅读文章的分论点一的内容是：One theory holds that the Chaco structures were purely residential, with each housing hundreds of people. 而在这个段落所对应的听力细节关键词就是：fewer fireplaces/ not enough for 100 people…。在书写过程中运用好转折关系就使得综合写作段落组织有序，衔接紧密，有很强的逻辑性。那么这个段落可以书写如下：The reading passage says that such housing structure was applied for residence, with each housing hundreds of people. On the other hand, the lecturer believes that there were fewer fireplaces providing for people application, let alone satisfying more than 100 people.
在独立作文中对逻辑性也有相关的要求：考生在提出论点之后，必须寻找相关的例证来支持和充实自己的论点。需要强调的是，在托福考试中考生可以发散地进行说理和寻找例证，但若是将自己所举的例证进行一定加工，按照由主到次、让步转折等顺序进行排列，则能更好地显示出各个例证之间的逻辑关系，让举例或是说理论证的过程更有层次性，这样的文章才称得上well-organized and well-developed. 以下面一道考题为例：
Do you agree or disagree with the following statement: Improving education is the most important thing in the development of a country.（题目）
Secondly, improving education seems to regulate the quality of population, which in turn promotes a favorable civilization. For instance, because of the lack of quality-oriented education, most students nowadays always perform badly, including showing no respect to elders, dropping litter here and there, and particularly arguing with others for simple things. Worse more, increasing number of news appears that the rate of teenage crime is rising up rapidly. If the education system is not regulated, the monolithic image will be destroyed, and will induce some negative impact to a country’s development. It turned that, education is playing an important and indispensible role in the development of a country.（考生文章1）
Secondly, improving education will improve the level of quality and makes the country become a civilization state. Take the example of the National University of Singapore; it has a strict teaching management system. At school, many people will take punishments because of a little thing like spiting and throwing garbage anywhere. To a certain degree, people will realize that a school is society in miniature. Gradually, their levels of quality will be higher and higher not only in a school but also in a country. So, the Singapore is known for its civilization. To sum up, the education has the most important effect on a country.（考生文章2）