(一)逗号的使用问题
逗号是用来帮助读者更好地进行阅读的。没有逗号句子就会发生碰撞，或者引起误解。例：
误解：If you cook Elmer will do the dishes.
误解：While we were eating a rattlesnake approached our campsite.
在合乎逻辑的地方加上逗号(after cook and eating),立刻一切就会变明白了。就不会错误地理解成为Elmer being cooked, the rattlesnake being eaten.
1)在等立复合连接词连接两个或多个句子的时候，在等立复合连接词前面加逗号。如: and、but、or、nor、for、so和yet。
Nearly everyone has heard of love at first sight, but I fell in love at first dance.
在一个表示引导的短语或句子后面用逗号(这个引导的短语或句子一般作状语)。
When Irwin was ready to eat, his cat jumped onto the table.
Near a small stream at the bottom of the canyon, we discovered an abandoned shelter.
在表示状语的句子或短语比较短的情况下，一般不用逗号。
In no time we were at 2,800 feet.
当分词短语在句首做状语，主要用于描述后面句子中紧跟着它的名词或代词时，要用逗号隔开(不管句子的长短)，这个逗号主要告诉读者他们就要明白这个人或事情的身份或情况了。
Knowing that he couldn't outrun a car, Kevin took to the fields.
Excited about the move, Alice and Don began packing their books.
注：其他表示引导的还有连接副词、过渡词和独立短语。
3)表示一系列的项目时要用逗号(三个或更多个)，这个项目可以是单个字、短语或者从句。
At Dominique's one cansgroupsfillet of rattlesnake, bison burgers,or pickled eel.
My uncle willed me all of his property, houses, and warehouses.
The activities include a search for lost treasure, dubious financial dealings, much discussion of ancient heresies, and midnight orgies.
4)在几个并列形容词之间用逗号或用and,而在相重或累积形容词前面不用逗号。
当两个或多个形容词来分别修饰一个名词时，它们叫做并列形容词。
Mother has become a strong, confident, independent woman.如果它们能够用and来连接(strong and confident and independent)，就叫做并列形容词。
当形容词不能分别来修饰时，这就叫相重或累积形容词。
Three large gray shapes moved slowly toward us.
并列形容词：Robert is a warm, gentle, affectionate father.
相重(累积)形容词：Ira ordered a rich chocolate layer cake.
5)用逗号隔开过渡语、插入语、独立短语和对比成分。
过渡语包括连接副词，如: however、therefore和moreover。
过渡短语: for example, as a matter of fact, in other words等。
Minh did not understand our language; moreover, he was unfamiliar with our customs.
Natural foods are not always salt free; for example, celery contains more sodium than most people would imagine.
当连接副词或过渡语出现在句子的一开始或者出现在一个独立句子的中间时，它经常要用逗号隔开。
The prospective babysitter looked very promising; she was busy, however, throughout the month of January.
As a matter of fact, American football was established by fans who wanted to play a more organized game of football.
注：如果连接副词或过渡语已经和句子融为一体，在阅读时无需停顿，就不再需要逗号了。
它们是: also、at least、certainly、consequently、indeed、of course、no doubt、perhaps、then和therefore.
Bill's typewriter is broken; therefore you will need to borrow Sue's.
插入语：提供补充评论或信息，常常出现在句中或者句末。
Evolution, as far as we know, doesn't work this way.
The striped bass weighed about twelve pounds, give or take a few ounces.
独立短语：独立短语常常修饰整个句子，它常常是一个名词加一个分词或分词短语。
His tennis game at last perfected, Chris won the cup.
Brenda was forced to rely on public transportation, her carshavingsbeenwrecked the week before.
对比成分：以not和unlike开始的显明对比成分应用逗号将其隔开。
Now that I am married, Jane talks to me as an adult, not as her little sister.
Celia, unlike Robert, had no loathing for dance contests.
6)用逗号隔开直接称呼名词，yes和no，反意疑问句的反问部分，以及温和感叹词。
Forgive us, Dr. Spock, for spanking Brian.
Yes, the Loan will probably be approved
The film was faithful to the book, wasn't it?
Well, cases like these are difficult to decide.
7)用逗号将动词和直接引语隔开。
Naturalist Arthur Cleveland Bent remarked,“In part the peregrine declined unnoticed because it is not adorable.”
Convictions are more dangerous foes of truth than lies, wrote Philosopher Friedrich Nietzsche.
8)用逗号将日期、地址、头衔和数字隔开。
日期：在日期中要用一对逗号将年和句子的其他部分隔开。
On December 12, 1890, orders were sent out for the arrest of Sitting Bull.
注：如果日期前置或者只有年和月则不用逗号。
The recycling plan goessintoseffect on April 1993.
January 1992 was an extremely cold month.
地址：地址中的成分或地点名称后面用逗号。邮编码前不用逗号。
John Lennon was born in Liverpool, England, in 1940.
Please send the package to Greg Tarvin at 708 Spring street, Washington, Illinois 61571.
称号、头衔：名字后面有称号，那么就要用一对逗号将称呼隔开。
Sandra Barnes, M.D., performed the surgery. (M.D.医学博士)数学：后面用逗号。
3，500〔or 3500〕
100，000
(二)句子不完整
在写作中一定要写完整的句子，即每个句子必须有它的动词(be动词或者实义动词)。一个完整的句子的结构应该是：1主语+谓语+宾语；2主语+谓语+状语；3主语+谓语+宾语+宾语补足语等句子形式。
1) Small portable machines which generate negative irons. (错)
They have invented small portable machines which generate negative irons. (正确)
2) They enjoy reading classic Chinese Literature. Such as the poetry by Li Bai and Du Fu. (错)
They enjoy reading classic Chinese Literature. such as the poetry by Li Bai and Du Fu. (正确)
注：hence后面可以直接跟名词而独立成句。
(三)避免粘连句
粘连句就是指用逗号连接数个独立的分句。
例：An old woman lived in the house, she surprised Hansel and Gretel they were eating parts of her home. (错)
该句中有3个主语(old woman, she, they)，三个动词(lived, surprised,和were eating)，分句可以用句号，分号(而不是逗号)或使用连接词。最普通的连接词是: and, but,so和or。连接代词有who, which,和that，还有表示时间连接词: before, after, when和so on。
上句可以改为：
①An old woman lived in the house. She surprised Hansel and Gretel. Theywere eating parts of her home.
②An old woman lived in the house and she surprised Hansel and Gretel and they were eating parts of her house.
③The old woman who lived in the house surprised Hansel and Gretel whilethey were eating parts of her house.
