Grammar and Punctuation
这篇文章是 Coursera 上 Academic English: Writing 专项课程的第一门课程的课程笔记。主要是一些语法和标点符号的使用，很基础，但是又很容易弄错。
共有三种类型的句子。
- 简单句
由主语和动词构成，又称作独立分句。
Sam washed his face.
- 复合句
由两个简单句或两个独立分句组成，将两个独立分句连接即可。
Sam washed his face, and he combed his hair.
- 复杂句
含有一个独立分句，和一个或多个从属分句。
Sam got dressed because it was time for school.
并列连词
并列连词有：
and / but / or / nor / yet / so / for
以下为使用并列连词的简单句示例。
- The computer is old and broken.
- Sam washed his face but not his hair.
- We will go to the park or the market.
- She bought apples, pears, and grapes.
注意到上面的第一句和最后一句都是使用 and 进行连接。但是第一句只有两个名词，所以不能用逗号连接；有三个及以上的名词时，一定要在名词相互之间用逗号连接。
复合句 (Compound Sentence)
第一种复合句
我们可以使用连词将两个主句连接起来构成复合句。常用的连词有：
and / but / or / nor / yet / so
形式如：
- The waiter brought us some water**, and** we looked at the menus.
- The cyclist used all of his energy**, but** he rode up the steep hill very slowly.
第二种复合句
我们可以使用转折词构成复合句。常用的转折词有：
therefore / however / in addition / thus / furthermore
similarly / otherwise / then / nonetheless / also
consequently / finally / indeed / likewise / moreover / nevertheless
这种类型的复合句还需要额外使用到分号和逗号，具体形式如下：
- I was late to work**; therefore,** my boss is not happy.
- Saving money is not easy**; however,** it is a good habit to follow.
以上是将转折词放于句子中间的用法，实际上，转折词还可以用于句子开头**（但是这种情况不属于混合句的范畴）**。如：
- Likewise, my teacher told me to start studying.
- Nonetheless, we need to start using water more wisely.
第三种复合句
当我们有两个句子非常紧密的联系的时候，并且有"and"的意思的时候，我们可以用分号直接连接。
如：
Susan is very healthy**;** she usually walks to work.
The music was loud**;** everyone was dancing.
总结
所以总的来说，总共有三种复合句。如下：
- 用逗号和连词（如 and, but, so）
- 用分号，转折词（如 therefore 或 however）和逗号
- 只用分号
状语从句 (Adverb Clauses)
以句子 “While Sam washed his face, we listened to music." 为例。从属子句的部分是，"While Sam washed his face"，因为有 "While" 所以这个子句是不能独立成句的。所以从属句是用状语从句连接词开始的。
每个状语从句能用两种不同的方法来写。如：
While Sam washed his face, we listened to music.
We listened to music while Sam washed his face.
Jeff ate an apple when he got home from work.
When Jeff got home from work, he ate an apple.
即，如果用从属句开始一个句子时，需要使用逗号连接；如果用独立从句开始一个句子时，则不需要使用逗号。
以下是一些常用的状语从句连接词：
after / although / while / when
before / since / if / because
even if / whether or not
in case / unless
so that / even though
更多使用逗号的情况
介绍性短语 (Introdutory Phrases)
介绍性短语一般独立放在句子开头，然后使用逗号将其与主句进行分隔。
- Due to the bad weather, our game was canceled.
- On Monday, my teacher announced a test.
- After dinner, Steve watched the news.
- Because of traffic, we were late to the theater.
- For several months, I have been playing the guirar.
打断性短语 (Interrupting Phrases)
通常我们可以在主语和动词之间看到打断性短语，但是实际上，他们可以放在句子的任何位置。
The mayor**, by the way,** will be at the meeting.
This is the reason**, therefore,** that you should buy a house.
Joe wants to buy a house**, too.**
还有类似于定语从句的打断性元素，如下
My roommate**, who hates seafood,** doesn't want me to cook shrimp.
The dress**, which I bought for tonight,** is too tight for me to wear.
关于转折词的使用
以转折词 therefore 为例。当它使用在复合句中时，形式如下
Jane loves books; therefore, she reads them all the time.
当它作为介绍性短语时，形式如下
Jane loves books. Therefore, she reads them all the time.
当它作为打断性短语时，形式如下
Jane loves books and, therefore, reads them all the time.
所以当转折词在不同的使用场景时，需要注意标点符号的使用。
平行结构
平行结构的句子，并列的部分都要使用同样的形式。如下
- He loves to swim and sleep.
- Cake and cookies are both fattening.
- We were hot, tired, and thirsty.
以下是常用的一些连接器，需要使用平行结构。
- ____ and ____
- ____ but ____
- both ____ and ____
- not only ____ but also ____
例句如下。
- I was looking for an apartment that was both close to my work and easy to afford.
- I want to find a gym that is not only close to my apartment but also affordable.
其中下划线部分都是形容词短语。
以修改下句为例。
He is afraid of being alone but not to die.
我们可以发现下划线部分并不是相同的形式，其中 being alone 是一个动名词，而 not to die 是一个不定式。所以我们可以改为下面的形式。
He is afraid of being alone but not dying.
句式多样性 (Sentence Variety)
句式多样性指的是使用多种类型的句子。
第一种方法实现句式多样性是使用不同类型的句子。有以下四种类型的句子
- 简单句 （Simple)
The grass grows in spring.
- 复合句 (Compound)
Grass grows in spring, but it dies in winter.
- 复杂句 (Complex)
Because it is too cold, grass doesn't grow in winter.
- 复合复杂句 (Compund-Complex)
Because grass needs warm weather, it doesn't grow in winter, but it grows in the summer.
第二种方法实现句式多样性是使用不同的句首。有以下几种开始句子的方式
- 副词 （Adverbs）
如 Quietly, Every day, Frequently
- 先行短语 (Prepositional Phrases)
如 In the morning, Due to stress, After work
- 其他转折词
如 The last reason ..., Another cause of...is..., For example, Furthermore
第三种方法实现句式多样性是使用不同长度的句子。
- 短句
使其精炼。但是我们大量使用或全部使用短句，会显得写作风格 choppy。
- 中等句
一般 10 到 15 词。
- 长句
一般 20 到 40 词。
第四种方法实现句式多样性是使用同义词。
- 重复重要的名词
需要注意的是，重要的名词是需要重复的。这样做，能让读者在你的思路中明白你要讲的东西。
The employee.......the employee......employees........
- 使用同义词来达到多样性
不重要的名词，可以使用同义词来避免文风显得无聊。
The employee.......workers........a worker.........the staff........employees.........
- 用不同的方式表达同一件事
The employee........the worker........the person working in an office.........a hired person..........someone employed.........
使用这四种方法，可以创建一种属于你自己的比较好的写作风格。
当写文章时，可以参考以下这些步骤。
- 选取话题 (Pick a topic)
- 进行一些写作构思 (Do some pre-writing)
- 书写文章主题 (Write a thesis statement)
- 写文章大纲 (Make an outline)
- 开始写作 (Begin writing)
- 修改和编辑 (Revise and edit)
当然，在前面的步骤，我们都不用考虑句式多样性，只需要在最后一步考虑就行。