四六級命題語料的選材原則是：
　　題材廣泛，包括人文科學、社會科學、自然科學等領域，但所涉及的背景知識應為學生所了解或已在文章中提供；
　　體裁多樣，包括敘述文、說明文、議論文等；(三種文體，也是大家平時閱讀和寫作最經常練習的)
　　仔細閱讀篇章難度適中，快速閱讀、聽力、改錯和完型填空的篇章難度略低；
　　詞匯范圍不超出《教學要求》中較高要求的詞匯，超出該范圍的關鍵詞匯，影響理解時，則以漢語或英語釋義。
　　看了這幾條四六級考試的命題原則后，相信大家都稍稍松了一口氣。
　　既然四六級考試命題的語料均選自英文原版材料，那我們有必要了解一下英語語料的特點。(主要從不同于漢語的方面來給大家介紹)
　　英語是非常注重邏輯明確的語言。英語注重文章的實質內容，講究層層推導、表達透徹，主題和主題句處于文章非常顯要的位置。如每一段的開頭或者結尾，在主題句之后，總有具體和細致的舉例、說明和闡釋來進一步深化主題，豐富內容。
　　我們先來看一下受漢語思維和表達影響很深的一篇作文：
　　From the picture, we can see that a beautiful American girl is in traditional Chinese costume and is smiling, as if she was asking us, “Am I like a Chinese” and speaking, “ I wish Chinese people happy like me。” It shows that with the faster pace of globalization, cultural differences are shrinking。
　　Over the ages, our Chinese people have been looked down upon by foreigners. But now, they are interested in our culture, wearing our clothes. What a change! It shows that we are getting stronger and more influential. It shows that Chinese people really stand up. In this respect, what reasons do we have to look down upon ourselves, our glorious culture and long traditional?
　　With the reform, China now is becoming a great country. She is going international. Her culture, both traditional and modern, will exercise an impact on the world. Let us work hard and make that possible in the nearest future。
　　上面的文章雖然分為三段式，但每一個段落差不多都是情緒激昂的口號，沒有實質性的內容，更無嚴密的說理和論述。這樣的短文，雖然語法上并不重大差錯，但因為內容空洞、缺乏邏輯而不能得到一個好的分數。
　　我們再來看一下，同樣的題目，比較符合英文思維方式和表達方式的作文是怎樣的：
　　⑴The American economic system is organized around a basically private-enterprise，market-oriented economy in which consumers largely determine what shall be produced by spending their money in the marketplace for those goods and services that they want most. ⑵ Private businessmen, striving to make profits, produce these goods and services in competition with other businessmen; and the profit motive, operating under competitive pressures, largely determines how these goods and services are produced. ⑶Thus, in the American economic system it is the demand of individual consumers, coupled with the desire of businessmen to maximize profits and the desire of individuals to maximize their incomes, that together determine what shall be produced and how resources are used to produce it。
　　⑴An important factor in a market-oriented economy is the mechanism by which consumer demands can be expressed and responded to by producers. ⑵In the American economy, this mechanism is provided by a price system, a process in which prices rise and fall in response to relative demands of consumers and supplies offered by seller-producers. ⑶If the product is in short supply relative to the demand, the price will be bid up and some consumers will be eliminated from the market. ⑷If, on the other hand, producing more of a commodity results in reducing its cost, this will tend to increase the supply offered by seller-producers, which in turn will lower the price and permit more consumers to buy the product. ⑸Thus, price is the regulating mechanism in the American economic system。
　　⑴The important factor in a private-enterprise economy is that individuals are allowed to own productive resources(private property)， and they are permitted to hire labor, gain control over natural resources, and produce goods and services for sale at a profit. ⑵In the American economy, the concept of private property embraces not only the ownership of productive resources but also certain right, including the right to determine the price of a product or to make a free contract with another private individual。
　　這篇文章的第一句就開門見山，明確了主題，提出美國經濟制度的特點是通過私有企業和市場導向調節作用。圍繞這一主題，文章的三個段落層層展開，環環相扣，每一段落各有側重。
　　第一段是講私有企業受盈利動機驅使進行生產和服務，這一動機決定企業的生產和服務方式，但更重要的是，這一動機取決于消費者的需求和愿望，即市場導向。這一段的最末一句是該段的段落主題句，實際上也是全文中心思想的另一種表述方式。
　　第二段開頭一句是該段的段落主題句，說明市場導向型經濟的重要特點之一是它有一個價格機制，價格的上漲和下跌反映并調節消費需求。圍繞這個主題句，第(2)、(3)、(4)句進一步闡述產品供需與價格浮動和消費需求的關系。
　　第三段的主題句也是該段的第一句，說明私有制企業的重要特色。該段的第二句是對主題句的進一步闡釋。