Another reason why people from the countryside transfer to the city is because of the modern conveniences that city living brings.
句型框架：主语从句+ is because of the 原因 +宾语从句 (包括主从，宾从两个名词性从句)
例句中，people from the countryside transfer to the city 是对题目关键信息的复述，句型中“原因”部分使用一个名词或名词词组。
Exercise： causes of congestion in megacities
Today more and more people rely on cars instead of walking， have less physical demands at work and prefer inactive leisure activities. This results in burning less calories and gaining weight.
句型框架：主语+ P.O.1 ， P.O.2 and P.O.3 . This results in doing sth.1 and doing sth.2.
例句中，三组P+O (谓语+宾语)是平行结构，第二句的”This” 指代三组P+O; doing sth.1 是result，doing sth.2是ultimate result。
Exercise： causes of overpopulation
雅思写作高分句型之3. “原因+细化方面解释” 式
Effluents are another by-product of industries which poses threat to the environment; leather and tanning industries， petroleum industries and chemical manufacturing industries create major waste products which are released directly into nearby streams without treatment， creating river pollution and causing harm to aquatic life.
句型框架：原因 is another by-product of … which poses threat to 主题词; 具体方面1，具体方面2 and 具体方面3 create … which are V+ed …out…， V+ing … …
Exercise： cyber crime
雅思写作高分句型之4. X(root cause)， Y(cause)， Z(result)式
Some people believe that global warming is a result of burning fossil fuels， as this causes increased carbon dioxide in the atmosphere.
解析： 这里我们把造成global warming (result)的原因分为burning fossil fuels(root cause)和increased carbon dioxide(cause)， 原因和根本原因，然后用适合的句式组织起来，使得逻辑论证层次更丰富。
句型框架： Some people believe that …(result) is a result of … (root cause)， as this causes ….(cause).
具体的句式组织还可以是以下五种，R(result)， C(cause)， RC (root cause)：
ü (R) has been directly affected by (RC)， as this allows for (C).
ü As a result of (RC) leading to (C)， (R) has been possible.
ü (RC)， thus allowing for (C)， has resulted in (R).
ü (RC) results in (C)， which in turn leads to (R).
ü Given (RC)， it follows that (C) would mean (R)
Exercise： cause and root cause of obesity
雅思写作高分句型之5. “双非谓语” 结构
Air pollution resulting from the factory and vehicle emission poses serious health concerns， considering the irritation of the eyes， nose， and throat， as well as increased risk of heart attack.
解析：把问题的原因和具体结果都用非谓语形式体现，主语只说关键词造成问题(概括性的名词)，即air pollution poses serious health concerns.
句型框架：关键词 resulting from… and … poses serious …concerns， considering … as well as…
例句中，描述air pollution 的形成原因部分resulting from和造成的健康问题具体包括什么considering都使用的是非谓语形式。
Exercise： cause and effect of social networking
This is only a possible version; you can create other correct sentences with the same structure
Exercise 1： causes of congestion in megacities
The reason why traffic congestion in megacities is increasing is because of the excessive growth of vehicle numbers that growing population brings.
Exercise 2： causes of overpopulation
Today， the advanced science have offered better medical facilities， promoted fertility treatment， and brought down death rate. This results in increasing population growth and becoming overpopulated gradually.
Exercise 3： cyber crime
Cyber-crime is another by-product of technology advancement which poses threat to the social security; internet fraud， online piracy and spread of violent and pornographic content create great risks which are available easily on the web without screening， causing harm to the social order.
Exercise 4： cause and root cause of obesity
Some people believe that obesity is a result of inactive life， as this causes less exercise and over eating.
Exercise 5： cause and effect of social media
Development of social networking resulting from technological advancement and fast-paced modern life poses serious social concerns， considering gradually alienated relationship between people， as well as deteriorated interpersonal communication skills.