议论文的整体结构
一篇好的议论文一般由三个部分构成，分别是#雅思考试(IELTS)# #雅思优秀议论文中的“三明治”结构#段（Introduction），主体段落（Body）与总结段（Conclusion）。这个结构很像三明治，其中#雅思考试(IELTS)# #雅思优秀议论文中的“三明治”结构#段与总结段就像最上层和最下层的面包，而主体段落为论证段，相对较为重要，就像三明治中间的肉和菜。其结构如下图所示：
Introduction
Body
Conclusion
通常情况下按照实际的需要，中间的主体部分（Body）又可以分成二到四个段落，其结构图分别如下：
Introduction
Body Paragraph 1
Body Paragraph 2
Body Paragraph 3*
Body Paragraph 4*
Conclusion
(注：*段落视需要而增加)
由于#雅思考试(IELTS)# #雅思优秀议论文中的“三明治”结构#段中最重要部分是中心句（Thesis statement），它是全文的立足点，决定文章的发展方向，覆盖全文；段落主题句（Topic sentence）是每一段的重点，覆盖各自所在的段落。因此，我们可以通过思考后得出议论文的中心句（Thesis statement）以及各主体段落主题句（Topic sentence）。此外，为求达到全文的统一性(Unity)和连贯性(Coherence), 考生们应当合理地安排中心句和各段的主题句的关系，使得中心句覆盖全文，使得各段的主题句很好地支持着中心句。如果中心句没有覆盖主题句，说明正文偏题了。如果中心句超过主题句，刚说明内容有遗漏，或者说内容不够全面。中心句各段的主题句的关系情况可由下面三张图表示：
Thesis Statement
Topic Sentence 1
Topic Sentence 2
Topic Sentence 3*
Conclusion
Thesis Statement
Topic Sentence 1
Topic Sentence 2
Topic Sentence 3*
Conclusion
Thesis Statement
Topic Sentence 1
Topic Sentence 2
Topic Sentence 3*
Conclusion
其中，第一张图显示了正文内容超过了中心句内容；第二张图则相反；第三张图中正文内容与中心句题才是相吻合的。（*号表示在双边型结构的文章中没有主体段的第三段。）
接下来我们通过实例来了解中心句, 主题句与总结段的布置。比如:
Topic1: Is it not necessary to learn the skill of cooking due to the success of convenience food and read-made meals?
Thesis statement: But in my opinion, cooking is a very important ability we should not lose.
Topic sentence 1: First of all, the fact is that ready-made meals are not usually that good for us.
Topic sentence 2: Moreover, it is extremely important for children to learn how to cook, so that they will be fully independent when they grow up.
Topic sentence 3: Speaking personally, I have always enjoyed experimenting in the kitchen, by cooking slightly unconventional meals.
Conclusion: In conclusion, although some use of convenience food is natural, no one should rely on it exclusively at the expense of home-cooked food. Not only is this unhealthy but it is also threatening important skills with extinction.
Topic 2: Who should be responsible for our old people?
Thesis statement: In my essay I would like to note four different models.
Topic sentence 1: Firstly, the company can be responsible for their retired employees.
Topic sentence 2: A second solution is that the government has to have the responsibility for the old people’s care.
Topic sentence 3: Another way of solving this problem is to give back the responsibility to the individual.
Topic sentence 4: A last solution is to go back to the old model of the big family who cares for all their members.
Conclusion: To sum up I have to admit that I can’t find a really good solution for this problem. All models have advantages and disadvantages. Certainly we will have to go on thinking.
Topic3: Should students in high school study music as a compulsory school subject?
Thesis statement: While some think the study of music in high school is a waste of valuable school time, musical training and study is an important part of educational development.
Topic sentence 1: It is true that when it comes to the study and application of music, not everyone is suited.
Topic sentence 2: On the other hand, it is quite well-known that music can play an important part in the development of the human brain.
Conclusion: While not every student may be musically inclined, the study of music is a valuable inclusion in any student’s course of study. In addition to being excellent for mental growth and development, students of music learn discipline, persistence and patience. Music should be a compulsory part of a high school student’s education.
议论文的段落结构
与议论文的整体结构布置相类似，在段落的写作中我们也用“三明治”结构来进行写作，即把段落分为主题句(Topic Sentence)，支持部分(Supporting Sentences)和结尾句部分(Concluding Sentences)。（注意：并不是每个段落都一定要有结尾句，重要地是要让这个段落自然地结束，不能给读者留下话还没有说完的感觉。）段落结构如下图如示：
PARAGRAPH
Topic Sentence
Supporting Sentences
Concluding Sentence
接下来我们通过实例来了解主题句，支持句与总结句的布置。比如：
1. Topic Sentence: First of all, the fact is that ready-made meals are not usually that good for us.
Supporting Sentences: They contain high levels of salt and sugar, not to mention harmful preservatives and artificial colorants.
Concluding Sentence: Therefore, a diet that is exclusively made up of such food is bound to be unhealthy.
2. Topic sentence: Teenagers find many ways to drive their parents crazy.
Supporting Sentence 1: First, they may dye their hair purple or they may shave their heads bald. They may also shred their new and expensive jeans and sit hours after hours in front of computers playing games or chatting with someone they never see.
Supporting Sentence 2: In addition, they spend hours windowing-shopping and on the phone. They have time to watch TV, but they do not have time to do their homework.
Supporting Sentence 3: Also, they are always too busy to clean their rooms, but they are never too busy to hang around in the streets.
Concluding Sentence: It is hard to be a teenager, but it is even harder to be parent of one.
3. Topic Sentence: In the second place, corporal punishment is by no means a desirable way of education a child.
Supporting Sentence 1: Numerous studies have shown that it does far more harm than good to children in their mental as well as physical development.
Supporting Sentence 2: For example, corporal punishment can give a child a sense of being treated unfairly, making him rebellious.
Concluding Sentence: This will be detrimental to the molding of the child’s character, and therefore should be avoided.
通过以上例子，我们可以清楚地把握雅思议论文结构（三明治结构），并可以通过练习一些雅思作文题目加以模仿，使得所写的文章结构良好，内容清晰、易读。良好的结构，清晰易读的内容也是好作文的一些特点。另外，在详细地学会如何发展段落以及组织整篇文章之后，考生们可以把更多的时间放在对一系列常考写作话题“脑力震荡”上，即尽量地准备更多话题的相关地ideas来组织论据。
