例1： There are several factors affecting climate. One factor is the mount of sunlight received. Altitude, or the height above sea level, also determines climate. The oceans have an effect on the climate of adjacent land. In addition, climate is influenced by the general circulation of the atmosphere.　　主題句指出影響氣候的幾個(gè)因素。然后用四個(gè)擴(kuò)展句說明四種因素。第一種是太陽光的接收量，第二種是海拔高度，第三句和第四句分別是海洋和大氣環(huán)流因素。　　2.2 次要推展句　　次要推展句是指對主要推展句作進(jìn)一步的事實(shí)分析和舉例說明。它從屬于某一個(gè)或某幾個(gè)推展句。　　例2：I dont teach because teaching is easy for me. Teaching is the most difficult of the various ways I have attempted to earn my living: mechanic, carpenter, writer. For me, teaching is a red-eye, sweaty-palm, sinking-stomach profession. Red-eye, because I never feel ready to teach no matter how late I stay up preparing. Sweaty-palm, because Im always nervous before I enter the classroom, sure that I will be found out for the fool that I am. Sinking-stomach, because I leave the classroom an hour later convinced that I was even more boring than usual.　　從屬于主要推展句2的三個(gè)次要推展句起著解釋說明作用，分別解釋red-eye, sweaty-palm, sinking-stomach的含義，這就更加形象生動(dòng)地證明了 teaching is not easy 這個(gè)主題。　　2.3 主要推展句與次要推展句的關(guān)系　　主要推展句與次要推展句的關(guān)系基本可以遵循下面的三部分規(guī)則。　　1〕每個(gè)主要推展句都應(yīng)該是對主題句中表示主要思想的關(guān)鍵詞的直接、明確的說明。　　2〕每個(gè)次要推展句都應(yīng)該說明它的主要推展句。　　3〕含有討論說明或分析的問題通常既要有主要推展素材，又要有次要推展素材。　　2.4 寫好推展句的方法　　主題句及關(guān)鍵詞確定后，開始選擇和主題有關(guān)的信息和素材。實(shí)質(zhì)上，針對關(guān)鍵詞測試每一個(gè)所選擇的素材就是一個(gè)分類的過程。有一種常用的方法就是句子展開前加以設(shè)問，然后解答，即設(shè)問-解答的方法。下面我們通過舉例來看一看這種分類過程是如何完成的。例3：　　假設(shè) Topic sentence: English is an international language?　　設(shè)問 Why can we say English is an international language?　　解答　　Because: English is spoken by pilots and airport control operators on all the airways of the world.　　Because: Over 70 percent of the worlds mail is written in English.　　Because: More than 60 percent of the worlds radio programs are in English.　　Because: Pakistan was once one of the British colonies.　　Because: Many members of the International Language Society are selected from English-spoken countries.　　從上面可以看出，最初的三個(gè)推展句是和關(guān)鍵詞an international language一致的。第四句和主題句不統(tǒng)一，盡管第四句會(huì)成為另一主題句很好的推展句。第五句說服力不強(qiáng)。　　當(dāng)然，在寫成段落時(shí)，沒有必要在每個(gè)句子開頭寫上 because，但是，在動(dòng)筆展開句子時(shí)，頭腦里要想著這個(gè)詞，這種檢驗(yàn)方法能幫助你把注意力集中在某個(gè)重心，圍繞主題思想層層展開。　　上面我們討論了主要推展句的一種展開方法。而展開次要推展句的方法與主要推展句類似，這里我們就不再復(fù)述了。

　　例1： There are several factors affecting climate. One factor is the mount of sunlight received. Altitude, or the height above sea level, also determines climate. The oceans have an effect on the climate of adjacent land. In addition, climate is influenced by the general circulation of the atmosphere.　　主題句指出影響氣候的幾個(gè)因素。然后用四個(gè)擴(kuò)展句說明四種因素。第一種是太陽光的接收量，第二種是海拔高度，第三句和第四句分別是海洋和大氣環(huán)流因素。　　2.2 次要推展句　　次要推展句是指對主要推展句作進(jìn)一步的事實(shí)分析和舉例說明。它從屬于某一個(gè)或某幾個(gè)推展句。　　例2：I dont teach because teaching is easy for me. Teaching is the most difficult of the various ways I have attempted to earn my living: mechanic, carpenter, writer. For me, teaching is a red-eye, sweaty-palm, sinking-stomach profession. Red-eye, because I never feel ready to teach no matter how late I stay up preparing. Sweaty-palm, because Im always nervous before I enter the classroom, sure that I will be found out for the fool that I am. Sinking-stomach, because I leave the classroom an hour later convinced that I was even more boring than usual.　　從屬于主要推展句2的三個(gè)次要推展句起著解釋說明作用，分別解釋red-eye, sweaty-palm, sinking-stomach的含義，這就更加形象生動(dòng)地證明了 teaching is not easy 這個(gè)主題。　　2.3 主要推展句與次要推展句的關(guān)系　　主要推展句與次要推展句的關(guān)系基本可以遵循下面的三部分規(guī)則。　　1〕每個(gè)主要推展句都應(yīng)該是對主題句中表示主要思想的關(guān)鍵詞的直接、明確的說明。　　2〕每個(gè)次要推展句都應(yīng)該說明它的主要推展句。　　3〕含有討論說明或分析的問題通常既要有主要推展素材，又要有次要推展素材。　　2.4 寫好推展句的方法　　主題句及關(guān)鍵詞確定后，開始選擇和主題有關(guān)的信息和素材。實(shí)質(zhì)上，針對關(guān)鍵詞測試每一個(gè)所選擇的素材就是一個(gè)分類的過程。有一種常用的方法就是句子展開前加以設(shè)問，然后解答，即設(shè)問-解答的方法。下面我們通過舉例來看一看這種分類過程是如何完成的。例3：　　假設(shè) Topic sentence: English is an international language?　　設(shè)問 Why can we say English is an international language?　　解答　　Because: English is spoken by pilots and airport control operators on all the airways of the world.　　Because: Over 70 percent of the worlds mail is written in English.　　Because: More than 60 percent of the worlds radio programs are in English.　　Because: Pakistan was once one of the British colonies.　　Because: Many members of the International Language Society are selected from English-spoken countries.　　從上面可以看出，最初的三個(gè)推展句是和關(guān)鍵詞an international language一致的。第四句和主題句不統(tǒng)一，盡管第四句會(huì)成為另一主題句很好的推展句。第五句說服力不強(qiáng)。　　當(dāng)然，在寫成段落時(shí)，沒有必要在每個(gè)句子開頭寫上 because，但是，在動(dòng)筆展開句子時(shí)，頭腦里要想著這個(gè)詞，這種檢驗(yàn)方法能幫助你把注意力集中在某個(gè)重心，圍繞主題思想層層展開。　　上面我們討論了主要推展句的一種展開方法。而展開次要推展句的方法與主要推展句類似，這里我們就不再復(fù)述了。