主題句是對全文的概括，是文章的主旨。它能在文章中起到“畫龍點睛”的作用。通常主題句出現在文章第一段的開頭，而后，全文對主題句所提出的內容進行解釋，擴展。下面我們通過實例來學習、體會“主題句”在具體情景中的運用

　　［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“在我們去海灘的路上發生了些不愉快的事”是對全文的總括。而后按照時間順序描述了“汽車拋錨，又關了空調，只能在酷熱中等待修車”。前文的愉快心情和后文又形成了對比，突出了煩躁的心情。

　　［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，說的比聽的多”是文章的主題句。而后作者對自己的性格和行為進行了詳細的描述。從兩大方面進行描述：善于表達自己成為眾人焦點，在和安靜的人聊天時能找到話題打破僵局。

同學們在寫作中，寫主題句時應注意以下幾點：

　　① 從整體上歸納幾個要點，將這些要點分布到不同的段落；

　　② 每段最好只有一個主題句，主題句具有概括性；

③ 主題句后的內容要能充分支撐其觀點。