怎样写一篇作文？
前几天我在文章为什么你需要开始英文写作？中建议每个人都开始动笔写点东西，但仍然有不少同学反映不知道如何开始，或者是写完之后不知道怎样修改。对此，我将在公众号上开设一个新专栏，对一些典型的习作进行分析，提出修改建议。同时我也会动手写一篇同题作文作为对比，以帮助大家掌握写作的基本思路。修改的步骤可参考：怎样修改一篇作文？
对于作文修改可以参考下面几个要点：
1) 用词：对照词典检查是否出现词不达意或用词冗余现象；
2）句式：检查是否有语法错误，比如主谓一致，垂悬句式，时态问题等。对于冗余句子可以进行精简。
3）逻辑：检查各个论点是否符合要求，论据是否充分有力，段落展开过程是否做到逻辑清晰。
下面要分析的文章是一篇雅思作文，题目是：
Overpopulation of urban areas has led to numerous problems. Identify one or two serious ones and suggest ways that governments and individuals can tackle these problems.
这是原始作文版本：
文/小蔡
Many countries of the world are currently experiencing problems caused by rapidly growing populations in urban areas, and both governments and individuals have a duty to find ways to overcome these problems.
Overpopulation can lead to overcrowding and poor quality housing in many large cities. Poorly heated or damp housing could cause significant health problems, resulting in illness, such as bronchitis or pneumonia. Another serious consequence of overcrowding is a rising crime rate as poor living conditions may lead young people, in particular, to take desperate measures and turn to crime or drugs.
In terms of solutions, I believe the government should be largely responsible. Firstly, it is vital that the state provides essential housing and healthcare for all its citizens. Secondly, setting up community projects to help foster more community spirit and help keep young people off the street is a good idea. For example, youth clubs or evening classes for teenagers would keep them occupied. Finally, more effective policing of inner city areas would also be beneficial.
Naturally, individuals should also act responsibly to address these problems, and the motivation to do this would hopefully arise if the measures described above are put into place by the government. This is because it will encourage people to have more pride in their own community and improve the situation.
Therefore, it is clear that the problems caused by overpopulation in urban areas are very serious. Yet if governments and individuals share a collective responsibility, then it may well become possible to offer some solutions.
点评版本：
Many countries of the world （of the world 属于赘词，去除）are currently experiencing problems caused by rapidly growing populations in urban areas, and both governments and individuals have a duty to find ways to overcome these problems. （同一个句子中出现了两个problems，不够简洁，可以改为 them）
Overpopulation can lead to overcrowding and poor quality housing （改为 housing quality）in many large cities. Poorly heated or damp housing （改为 houses 更好）could cause significant health problems, resulting in illness （可去除）, such as bronchitis or pneumonia. Another serious consequence of overcrowding is a rising crime rate as poor living conditions may lead young people, in particular, to take desperate measures and turn to crime or drugs. （此处逻辑有问题，房屋居住条件差与年轻人走向犯罪并没有必然联系。可以改成 Competition for jobs is getting intense due to overpopulation. That means more young people will be out of work, and to make a living, some of them may turn to crime.）
In terms of solutions, I believe （I believe 可以去掉） the government should be largely responsible. Firstly, it is vital that the state provides essential housing and healthcare for all its citizens. （提供住房和医疗给所有市民有点不切实际，可以改成 provides housing subsidies and healthcare for poor citizens）Secondly, setting up community （句子中出现了两个 community，可以去掉一个或者设法进行同义词替换） projects to help （help去除） foster more community spirit and help （help去除）keep young people off the street is a good idea. （is a good idea 表达有点口语化，可以改成 ...keep young people off the street also helps）For example, youth clubs or evening classes for teenagers would keep them occupied. Finally, more effective policing of inner city areas （inner city 本身包含有 area 的概念，areas 应去掉）would also be beneficial.
Naturally, individuals should also act responsibly to address these problems, and the motivation to do this would hopefully arise （motivation 与 arise 搭配不妥，可以改成 motivation will be strengthened） if the （the 去除）measures described above are put into place by the government. This is because it will encourage people to have more pride in their own community and improve the situation. （这一段逻辑有问题，整段并没有写到个人对于解决拥挤问题的方法，而是在强调政府的作用）
Therefore, it is clear that the problems caused by overpopulation in urban areas are very serious. （这句话与文章主题无关，人口过多带来严重问题已经是题干中的既定事实，不需要再三强调）Yet if governments and individuals share a collective responsibility, then it may well become possible to offer some solutions. （句子太拖沓且指代不明，可以改成 then problems attendant on overpopulation will become solvable）
总结：
文章在语法和用词上没有太多硬伤，但部分表达可以更加简化。主要问题在于论证逻辑，例如第二段中出现的居住条件差与年轻人犯罪的关系，第四段中关于个人采取的措施等。
解决该问题的办法是仔细推敲文章中每一句话与上下文以及文章主题的联系。如果实在看不出逻辑上的漏洞，可以将文章翻译成中文，这样论证中存在的问题会更加一目了然。
下面是我写的同题作文。文章思路如下：
分析人口过多带来的两大问题：交通拥挤以及住房问题。
政府的解决方案：
（1）针对交通问题：修建交通基础设施
（2）针对住房问题：做好城区规划；发放住房补贴以及无息贷款
个人的解决方案：
（1）针对交通问题：住在离公司近的地方，缓解交通压力
（2）针对住房问题：与家人或朋友合租，减小住房负担
People flock to cities in search of a better life, but at the same time bring forth problems such as traffic congestion and rising house prices, posing a challenge both to governments and individuals.
Overpopulation leads to traffic conundrums. The influx of people overloads city transport systems, leaving in its wake traffic jams in which daily commuters have to spend long hours fuming on trains. As they expend more time on the road, their time spent on meaningful work would decline accordingly, resulting in a significant production loss to society. The rise in population also gives birth to housing problems, for example rent increases and high property price, since the competition for a place to shelter gets ever more intense. Consequently, those less well-off have to live on the outskirts of cities where the cost of living is lower, often at the expense of commuting time and life satisfaction.
Governments can take measures to resolve these issues. One concerns building infrastructure. Opening more commuter routes will relieve stress on public transport, and city officials should encourage residents to travel by bus or train. As to housing problems, good urban planning and policy help. More high-rise apartment blocks could be built in densely populated urban areas to increase housing stock and lower price. Doling out housing subsidies and low-interest loan also lightens the burden of would-be home buyers.
Individuals for their part make contributions too. By choosing to live close to their workplace, office workers cut commuting time and reduce road traffic. Young people can also opt to share a roof with their friends or families to bring living costs down.
Problems attendant on overpopulation are numerous but not insolvable. Governments and individuals should make a concerted effort to cure the ills of city life, so as to ensure more can enjoy the virtue of it.