段落是文章的縮影。寫(xiě)好了段落，就能比較成功地寫(xiě)出較好的文章。經(jīng)過(guò)中學(xué)英語(yǔ)基礎(chǔ)階段的學(xué)習(xí)之后，大學(xué)英語(yǔ)的寫(xiě)作重點(diǎn)就從選詞造句轉(zhuǎn)移到了聯(lián)句成段和聯(lián)段成篇上。進(jìn)行段落層次上的寫(xiě)作訓(xùn)練，是寫(xiě)好英語(yǔ)文章的關(guān)鍵一環(huán)。下面介紹的是段落結(jié)構(gòu)。
段落（ paragraph ）是由表達(dá)單一中心思想（controlling idea or central idea ）的一組句子（包括主題句 topic sentence,推展句supporting sentences及結(jié)論句concluding sentence）構(gòu)成，是文章結(jié)構(gòu)的基本獨(dú)立單位。本講我們將就主題句和中心思想這兩個(gè)方面展開(kāi)討論。
主題句與推展句
1． 主題句
主題句（topic sentence）是表達(dá)段落主題的句子。它用以概括段落大意，要求全段其他文字都圍繞它展開(kāi)。請(qǐng)看下例：
My mother has passed along to me certain rules for getting along with others. Don't argue with parents; they will think you don't love them. Don't argue with children; they will think themselves victimized. Don't argue with spouses; they will think you are a tiresome mate. Don't argue with strangers; they will think you are not friendly. My mother's rules, in fact, can be summed up in two words: Don't argue.
主題句中提出的 "certain rules" 指的是什么？展開(kāi)句中通過(guò)四個(gè) "Don't argue --" 逐一加以交代。從結(jié)構(gòu)來(lái)看，這是一個(gè)比較典型的段落，它包括了主題句，推展句和結(jié)論句（即本段中的末句）?！ ?BR> 1．1 主題句的位置
主題句通常放在段落的開(kāi)端，其特點(diǎn)是開(kāi)門(mén)見(jiàn)山地?cái)[出問(wèn)題，然后加以詳細(xì)說(shuō)明。其作用是使文章的結(jié)構(gòu)更清晰，更具說(shuō)服力，便于讀者迅速地把握主題和想象全段的內(nèi)容。主題句可以放在段中起到承上啟下的作用，或放在段尾起概括全段的作用。但初學(xué)者比較難于掌握，因而在四級(jí)考試中，考生應(yīng)盡量采用將主題句放在段落開(kāi)頭的寫(xiě)作手法。
例1: Our life today depends very much on energy. In towns and in villages, on farms and in factories, machines have made life easier than it used to be. The machines use energy, and energy is needed for heating, lighting, communications, carrying goods -- everything. Factories and industrial plants use a great deal of energy to make the things that we use and buy and sell.