主体段落一般由主题句和扩展句构成。主题句一般放在第一句，是段落核心，用来概括全段内容。主题句分为笼统主题句和具体主题句。笼统主体句的作用是引出下文，点明方向，具体主题句则概况下面内容的核心主题。仅有主题观点是不够的，还要对其进行论证，也就是围绕主题进行论证，对其进行说明、叙述、举例及论述。
一、用一些研究、调查、发现、科学家及权威人士的观点或组织机构的研究结果加以论证，并引用数据作为支撑。此论证方法的好处就是比较权威客观，更有说服力。
If people move to live in different places, they will have more opportunity for improving their lives. According to a survey conducted by the Chinese Academy of Social Sciences, 55% of urban Chinese had changed their living place at least once in their lifetime by 2000, an increase of 30 percent as compared with that of 2 decades ago. Chinese sociologists agree that this trend is most likely to continue with the development society. Statistics indicate that people who moved at least once in their lifetime enjoy a much higher living standard than those who never moved.
本段先是引用中科院的调查数据加以论证，然后用某些专家和数据继续加以论证。有一点值得注意，很多考生并不知道真实的数据，考试中往往是自己的发明创造。所以没有把握的情况下，尽量不要去写那些众所周知的人或者机构，可以模糊地用某个机构或某个学者，数据上也千万不要太夸张，只要能达到有力够论证自己的观点即可。
二、通过比较和对比方式来论证，这样两个事物、行为或者观点的利弊就非常明显。
Those who believe in the measure say that students benefit a lot from traveling or working for a year before their formal university education. First, they can more broadly acquainted themselves with the society, deepen their understanding of the outside world, and thus better coordinate their objectives of learning with the needs of the society. In contrast, by immediate entrance to university they can not steer the direction of their study well and may display a poor combination of the theory with practice. Second, study at high school is really exhausting, especially when to win college admission. So it is necessary to grant these children a relatively long period of relaxation or buffer, say, traveling or working for a year, to loosen the chords of their brain, so that when they go back to school later again, they can become completely refreshed and rejuvenated.
这篇文章是关于上大学前是否应该用一年的时间来旅游或者工作进行论证。此段的主题是学生在进入大学学习之前花一年时间进行旅游或工作的话，会让他们受益匪浅。对比点是：进入大学之前一年进行旅游或工作有利于让学生广泛了解社会，加深他们对外界的理解，因此能让他们更好地协调好学习目标和社会的需要。相对比之下，直接进入大学学习的话，他们不能够把握学习的方向，而且有可能会产生理论和实践相脱节。通过此番对比，旅游或工作一年对于即将步入大学的学生们的好处是显而易见，段落的主题句得到有力的论证。
三、通过假设进行正反论述。
Then, since the transportation system is the lifeline of a country’s economic activities, its paralysis would lead to the disintegration of the economy, either industry of farming or daylife. Suppose all the means of transportation were halted for lack of oil, factories with insufficient raw materials would have to close, workers would be out of work, and ripe farm crops would have to stay in the fields at the mercy of rain and storms. People would try to store food and the price of all commodities would go up. If we take those power stations run by oil into account, situations would become even worse. In this sense, oil decides the fate of the whole economy and that of the government. |
