在托福写作考试中，议论文写作比较常见。一般来说议论文写作我们主张三段论结构式。即是：引言段-主体段-结论段的“三步曲。如何让文章更连贯更加理据充分，北京新航道老师经过多年的经验总结的，关于三段论的几个基本原则，和大家分享一下， 希望能帮助大家的写议论文。

　　这几个简单原则包括：

　　1.Write a topic sentence for each paragraph you plan to write. Each topic sentence should relate to your thesis statement and introduce what the paragraph will be about. If you find that the topics you want to discuss do not support the thesis statement you have written, revise your thesis statement or reconsider your topic sentences.

　　(每个主体段都必须有一个明确的主题句)

　　2.Write ideas that support your topic sentences. The topic sentence for each paragraph tells the reader what the paragraph will be about. The ideas stated in the rest of the paragraph should all relate to the topic sentence.

　　(支持句必须围绕主题句展开)

　　根据第2条的原则，我们来看看下面这个主体段：

　　Hobbies are important for many reasons. First, a hobby can be educational. For example, if the hobby is stamp collecting, the person can learn about the countries of the world and even some of their history. Second, engaging in a hobby can lead to meeting other people with the same interests. A person can also meet other people by going to the school. Third, a person's free time is being used in a positive way. The person has no time to be bored or get into mischief while engaged in the hobby. Finally, some hobbies can lead to a future job. A person who enjoys a hobby-related job is more satisfied with life.

　　这段话的topic sentence很明显-“Hobbies are important for many reasons”，之后的支持句从三方面阐述hobby的重要性(first, second, third)，但段中这句话"A person can also meet other people by going the school"与hobby重要的原因没有关系，因此削弱了整个段落的连贯性与统一性，应该被去掉。

　　3.Add details. To write a more fully developed paragraph, you need to add details to your supporting ideas. Your details can be facts, examples, personal experiences, or descriptions.

　　(需要用多种方式提供细节展开段落)

　　根据第3条的原则，我们来看下面这个段落：

　　The Smithsonian Institution is worth visiting for a number of reasons. The Smithsonian Institution comprises various museums that offer something for everyone. These museums include the National Museum of History and Technology, the National Aeronautics and SpaceMuseum, the National Collection of Fine Arts, the National Museum of Natural History, and several others. A person can do more than just look at the exhibits. For example, in the insect zoo at the National Museum of Natural History, anyone who so desires can handle some of the exhibits. The museums provide unforgettable experiences. In climbing through the Skylab exhibit at the National Aeronautics andSpaceMuseum, I was able to imagine what it would be like to be an astronaut in space. Movies shown at regular intervals aid in building an appreciation of our world. In the National Aeronautics andSpaceMuseum, there is a theater that has a large screen. When the movie is shown, it gives the viewer the feeling that he or she is in the movie itself, either floating above the Earth in a hot-air balloon or hang gliding over cliffs.

　　这是一个成功的主题段，请注意这段话段落细节展开的几种形式-提供事实、举例、个人经历和描述。我们把这个段落拆分后进行分析：Topic sentence，来源：北京新航道托福培训

　　(主题句)The Smithsonian Institution is worth visiting for a number of reasons.

　　Supporting idea 1

　　(支持理由1)The Smithsonian Institution comprises various museums that offer something for everyone.

　　Details – facts

　　(细节展开-提供事实)These museums include the National Museum of History and Technology, the National Aeronautics andSpaceMuseum, the National Collection of Fine Arts, the National Museum of Natural History, and several others.

　　Supporting idea 2

　　(支持理由2)A person can do more than just look at the exhibits.

　　Details – examples

　　(细节展开-举例)For example, in the insect zoo at the National Museum of Natural History, anyone who so desires can handle some of the exhibits.

　　Supporting idea 3

　　(支持理由3)The museums provide unforgettable experiences.

　　Details – personal

　　experience

　　(细节展开-个人经历)

　　In climbing through the Skylab exhibit at the National Aeronautics andSpaceMuseum, I was able to imagine what it would be like to be an astronaut in space.

　　Supporting idea 4

　　(支持理由4)Movies shown at regular intervals aid in building an appreciation of our world.

　　Details – description

　　(细节展开-描述)In the National Aeronautics andSpaceMuseum, there is a theater that has a large screen. When the movie is shown, it gives the viewer the feeling that he or she is in the movie itself, either floating above the Earth in a hot-air balloon or hang gliding over cliffs.

　　上面给大家总结的几个原则，希望大家在实际的托福写作中能够应用。从而让自己的文章更充实，更加丰满，行文连贯，堪为一篇好文章，拿也不是那么难了。

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