托福写作高分句型之1. 双名词从句式

　　Another reason why people from the countryside transfer to the city is because of the modern conveniences that city living brings.

　　解析：适用于引入原因(带题目关键词)

　　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

　　托福写作高分句型之2. 三组P+O式

　　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.

　　解析：适用于解释句，说明三种具体原因或结论段总结原因和结果

　　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

　　托福写作高分句型之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.

　　解析：适用于说明一个原因(论点)后紧接着把这个原因的几个方面具体化论述。

　　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 ….without…, V+ing …..to …

　　例句中，which are…的部分是定语从句，Ving…to…是非谓语用法。

　　Exercise: cyber crime

　　托福写作高分句型之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

　　托福写作高分句型之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

　　句型虽好，可不要贪心。具体写作时并不是复杂句越多越好，一篇文章中用1-2个这样的逻辑句型就可以，大多数还是要使用基础句型，逻辑清晰，准确表达更重要。

　　托福写作高分句型答案:

　　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.