主题句是表达段落主题的句子。它用以概括段落大意，要求全段其他文字都围绕它展开。请看下例：
My mother ha paed along to me certain rule for getting along with other. Dont argue with parent; they will think you dont love them. Dont argue with children; they will think themelve victimized. Dont argue with poue; they will think you are a tireome mate. Dont argue with tranger; they will think you are not friendly. My mother rule, in fact, can be ummed up in two word: Dont argue.
主题句中提出的certain rule指的是什么?展开句中通过四个Dont argue -- 逐一加以交代。从结构来看，这是一个比较典型的段落，它包括了主题句，推展句和结论句。
1.1 主题句的位置
主题句通常放在段落的开端，其特点是开门见山地摆出问题，然后加以详细说明。其作用是使文章的结构更清晰，更具说服力，便于读者迅速地把握主题和想象全段的内容。主题句可以放在段中起到承上启下的作用，或放在段尾起概括全段的作用。但初学者比较难于掌握，因而在六级考试中，考生应尽量采用将主题句放在段落开头的写作手法。
例1: Our life today depend very much on energy. In town and in village, on farm and in factorie, machine have made life eaier than it ued to be. The machine ue energy, and energy i needed for heating, lighting, communication, carrying good -- everything. Factorie and indutrial plant ue a great deal of energy to make the thing that we ue and buy and ell.，WWw.hAOzuowEn.com