我們都知道，在職研究生英語考試作文要有開頭、正文和結尾，也是由各個段落組成的。然而，就像我們語文寫作文一樣，英文作文也勢必要有中心思想，而每段也要有一個主題句，起到概括的作用。
幾個主題句的精彩寫作不僅會讓文章條理分明，更能夠很好的詮釋文章主題思想，可謂是文章的架構靈魂，所以，寫好主題句對一篇文章的好壞有著至關重要的作用。
定義：主題句為一個完整的句子，用以概括、敘述和說明該段的主題。
位置：主題句一般位於段首，也可置於段尾或段中，考生最好放在段首，這樣較易掌握和構思。
例如：
位於段首：在英文中，大部分段落的第一句便是主題句。開門見山地提出問題，後面的擴充套件句圍繞主題句加以說明、支援、補充和解釋。
An important part of police strategy, rapid police response is seen by police officers and the public alike as offering tremendous benefits. The more obvious ones are the abilities of police to apply first aid life saving techniques quickly, and the greater likelihood of arresting people who may have participated in a crime. It aids in identifying those who witnessed an emergency or crime as well as in collecting evidence. The overall reputation of a police department too is enhanced if rapid response is consistent and this in itself promotes the prevention of crime. Needleto say rapid response offers the public some degree of satisfaction in its police force.
位於段尾：主題句位於段尾便於總結全段的內容，給讀者以深刻的'印象，是寫作中的一種演繹方法。
At present rates of demand, the world has enough oil to last for more than 40 years, enough gas for more than 60 years and enough coal for more than 230 years. Naturally, demand will increase; but so will reserves as companies explore more widely and costs fall. Since 1970 viable reserves of oil have almost doubled while those of gas have leapt three-fold. One distant day a crunch will come, but as it approaches fossil-fuel prices will rise, ma-ki-ng alternative forms of energy, perhaps including nuclear power, competitive. That is no reason to spend on nuclear now.
位於段中：位於段中的主題句起承上啟下的作用，這類主題句多起轉折作用，一般由“but, however, yet, anyhow, nevertheless”等詞連線，用於引起下文。
What we teach ourselves sometimes, indeed, is more useful than what we learn from others. Some great men had little or no schooling. But these great men probably studied harder by themselves than most boys do in school. The greatest minds do not necessarily of those who have never been able to distinguish themselves at school, have been very successful in life later. It has been said that Wellington and Napoleon were both dull boys at school, and so were Newton and Albert Einstein.
無主題句：有的段落中無主題句，段落的主題思想通過文章內容來提示，這種方法能促使讀者對文章內容進行思考和分析，但考生一般不宜在考試中採用這種方法：
Money may be deposited or withdrawn from branches of the credit unions and banks during businehours from Monday to Friday (but not on public holidays) or 24 hours a day from the many on-campus automatic teller machines. Businehours for financial institutions vary, but credit unions are usually open from 9 am to 5 pm weekdays, and, generally, banks are open from am to 4 pm (5 pm on Fridays). Some services are available on Saturday mornings in selected areas. While prices often compare favorably with prices overseas, because Australia is a large and exciting country it is very easy to overspend, especially if on a tight budget.
