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。通常主题句出现在文章第一段的开头，而后，全文对主题句所提出的内容进行解释，扩展。下面我们通过实例来学习、体会“主题句”在具体情景中的运用

　　［范例1］
　　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!

第一句“在我们去海滩的路上发生了些不愉快的事”是对全文的总括。而后按照时间顺序描述了“汽车抛锚，又关了空调，只能在酷热中等待修车”。前文的愉快心情和后文又形成了对比，突出了烦躁的心情。

　　［范例2］
　　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.

第一句“我是外向的男孩，说的比听的多”是文章的主题句。而后作者对自己的性格和行为进行了详细的描述。从两大方面进行描述：善于表达自己成为众人焦点，在和安静的人聊天时能找到话题打破僵局。

同学们在写作中，写主题句时应注意以下几点：

　　① 从整体上归纳几个要点，将这些要点分布到不同的段落；

　　② 每段最好只有一个主题句，主题句具有概括性；

③ 主题句后的内容要能充分支撑其观点。