开始部分（opening paragraph） 说出文中的要点、核心问题。
正文部分（Body paragraphs） 围绕主题开展叙述、讨论。
结尾部分（concluding paragraphs） 对全文的总结和概括。
主题句是对全文的概括，是文章的主旨。它能在文章中起到 画龙点睛 的作用。通常主题句出现在一篇文章的开头，而后，全文对主题句所提出的内容进行解释，扩展。
Something unpleasant happened to us on our way to the beach. In the morning, while we were waiting to buy train tickets in the railway station, a bus driver came over to us. He told us he also was going to the beach, the ride was cheap, and the bus was air-conditioned. We felt grateful and got on his bus. As we were talking happily on the way, the bus suddenly stopped. The driver said he needed two hours to repair the engine. While he was working on the engine, he turned off the air-conditioner. He actually took four hours to finish his job, and we spent the whole morning sweating in the heat!
I am an active boy and I talk more than listen. When I talk with my friends, I m always ready to express myself. I m not afraid to tell others what I think. I am usually the focus of the attention because I often have lots of ideas that interest everyone. In my opinion, people should share and exchange each other s ideas. But when I am with the quiet people, I feel the air is frozen. I m always trying to find a topic and start a conversation. In this way, people will like me and feel happy.
In a word, I am optimistic and active and I can make everybody as confident as me.