歷年四級考試中的“How I Overcome Difficulties in Learning English”、“My Ideal Job”以及圖表作文的第一段都屬于說明文的范疇，如，2002年6月的根據坐標圖寫題為“Students Use of Computers”的作文。

　　說明文必須按一定的順序進行說明：時間順序、空間順序、邏輯順序或認識順序，選擇具體的特點和細節來說明。

　　所以，說明文的思路要圍繞說明順序、事物的特點和細節展開。例如：

　　范文點評

　　A Famous Clock

　　When you visit London， one of the first things you will see is Big Ben， the famous clock which can be heard all over the world on the B.B.C. If the Houses of Parliament had not been burned down in 1834， the great clock would never have been erected. Big Ben takes its name from Sir Benjamin Hall who was responsible for the making of the clock when the new Houses of Parliament were being built. It is not only of immense size， but is extremely accurate as well. Officials from Greenwich Observatory have the clock checked twice a day. On the B.B.C. you can hear the clock when it is actually striking because microphones are connected to the clock tower. Big Ben has rarely gone wrong. Once， however， it failed to give the correct time. A painter who had been working on the tower hung a pot of paint on one of the hands and slowed it down!

　　【點評】這是《新概念英語》中的一篇經典說明文，介紹了世界著名的“大本鐘”。文章開篇指明該鐘位于英國倫敦，且全世界的人們通過BBC就能夠聽到鐘聲。接下來講述了“大本鐘”的由來，特點——不僅外型巨大，而且走時準確，在結尾處講了“大本鐘”的一個幽默的小插曲——油漆工把油漆桶掛在指針上，把鐘弄慢了。細讀這篇文章，我們不難發現，區區159個單詞就把“大本鐘”的光輝形象牢牢地刻在讀者的腦海里，為什么?本文基于事實，分析了主題的來龍去脈，語言簡潔又不失生動貼切，作者態度客觀又充滿幽默，使讀者既“明白了事理”，又對事物有較完整明晰的了解認識，此乃說明文之真諦也。

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