一、篇章结构(一)先有规矩，然后才干从心所欲，不逾矩议论文的写作，住往从正反两方面来论述，且都有其约定俗成的议论形式，即从“主题句一正面论述，背面论述一结论”四大块去营造文章的基本结构(四块论)。例如，某标题要求论述“学校规则‘课间学生只能呆在自己的教室里’对吗?”这一话题。假如作者以为学校的规则不对，他就应该在文章第一块(段)亮出自己的观念：There is currently much discussion about whether students should stay in their own classrooms or not during break times.Personally I believe that—。而第二块应该从正面论述“课间不能只呆在自己的教室里”的理由。比如能够说：I would argue that break times are our only opportunity to choose what we want to do. 第三块则从背面观念，即“课间只能呆在自己的教室里”动身，驳斥对方观念或进一步论述己方观念。例如能够说：Another reason why people say that students have to stay in their own classes at break times is that it would be difficult to organize dinners.最后一块(段)则用不同的语言再次强调已方观念。乍一看去，议论文“四块论”似乎有“八股文”的嫌疑，但“四块论”契合人的认知规律，所以值得多多模仿和操练。
1.Firstly，it is very convenient in daily life.There are many shops and supermarkets in a city.I can buy everything I need easily in these places.When I am sick，I can easily see a doctor in any clinic or hospital.Transport services are good in a city.when I want to go somewhere，I can take a bus，a train or something else.There are also many kinds of entertainment in a city.Public buildings(such as libraries)and parks can easity be found in a city，too.
2.First.it is convenient and comfortable to live in a city.To begin with，there is good housing in a city，as all the houses and flats are well-equipped with good facilities and surrounded by modern amenities such as places of entertainment，public libraries and parks.而中心句的写法也有考究。中心句必需能高度概括所在段落的论据，它的关键词应该在每—个论据中都有重复或恰当表现。那种无关痛痒的叙述或阐明性的句子，是不适合用作中心句的。例如：
1.Students always feel relaxed and happy during breaks.(叙述性句子)
2.Break times are scheduled for about 10 minutes.(阐明性句子)
以下即是论述“学校规则‘课间学生只能呆在自己的班级里’对吗?”的一篇学生习作：Although some people believe that students should stay in their own classrooms during break times，I would like to argue that we should be allowed to spend break times in another class. The most important reason for believing that is that many students have friends in other classes.We spend all day in our own classroom，and break times are the only time we have to spend with other friends.It can become very tedious(令人厌倦的)to have to spend even more time with the same people. A further reason for allowing student to choose where they spend their break times is that it would stop arguements.If students are forced to spend time with classmates who are not good friends，they can annoy each other.This leads to problems that have to be sorted out by teachers. Teachers argue that we all should stay in our own classes，because it is then easier to know what is going on.They say that it is difficult to keep track of students when they are walking round the corridors.However，students could be given the chance to choose a different classroom to spend the whole break time in.That would mean that there would not be any students in the corridors. As I have explained，although it might be a little easier to manage when everyone stays in their own classroom，it would make break times happier for all students if they were allowed to choose where they spent their time.这篇范文契合“四块论”的基本形式，正反论述统筹，结构严谨，中心突出。