逗號
在用逗號時，有幾種基本規則，但逗號的用法其實還有很多種語，像是用逗號來添加句子的意思或強調某件事情、要點或意義。
雖然老師常這麼教：逗號是用來方便我們在句中有「呼吸的空間」。但更精確的說法，是用來組織多個想法或邏輯。另外，先不論文法上的規則，多數人總會在句中加逗號來確保意思有表達清楚；而有時如果句子沒逗號也不會影響意思，就乾脆不加逗號。
在列舉的片語、字詞或子句之間做分隔
在列舉事物時，一般會用逗號來分隔各項事物。但列舉到最後兩項事物時，通常會在倒數第二項的字尾標上逗號，再接「and」或「or」來舉出最後一項。這種逗號在編輯的術語中，叫做「牛津逗號」。
一系列的獨立子句（多個句子）
舉例
- I met Harry, we went for a swim together, and afterwards Harry went home.
- I like your son, I might even love him, but he is not a very good soccer player.
一系列的名詞
舉例
- For dinner I had soup, fish, chicken, dessert, and coffee.
- This afternoon I went to Oxford Circus, Picadilly, Hamstead, and Gatwick Airport.
一系列的形容詞
列舉一系列的形容詞時，通常也會用上逗號。然而，如果形容詞是在修飾別的形容詞，則不必以逗號分隔（請見第三個例句）。
舉例
- She was young, beautiful, kind, and intelligent.
- The house we visited was dark, dreary, and run-down.
- She was wearing a bright red shirt.
一系列的動詞
舉例
- Tony ran towards me, fell, yelled, and fainted.
- The boy leapt, spun, twisted, and dove into the water.
一系列的片語
舉例
- The car smashed into the wall, flipped onto its roof, slid along the road, and finally stopped against a tree.
- The dog leapt into the air, snatched the frisbee in its mouth, landed, and ran off into the forest.
添加額外的資訊
用逗號來添加非限定關係子句或非必要性的細節或評論，在嵌入的子句前一個字的字尾還有子句的句尾，都會加上逗號。
舉例
- China, one of the most powerful nations on Earth, has a huge population.
- Jason's grandmother, who was born in 1930, lived through the Second World War.
- Cats, unlike dogs, do not respect their masters.
- My friend, Jim, likes to go scuba diving.
分詞片語
舉例
- Hearing that her father was in hospital, Jane left work immediately.
- Walking to the bus stop that morning, Sam knew it was going to be a special day.
附加問句
舉例
- She lives in Paris, doesn't she?
- We haven't met, have we?
插入的詞語
舉例
- Yes, I will stay a little longer, thank you.
- No, he isn't like other boys.
- Wait, I didn't mean to scare you.
最後的小提醒
如果把逗號加在錯誤的地方，可會導致整個句子的意思不同。觀察這兩個句子吧：
I detest liars like you; I believe that honesty is the best policy. = 我憎恨像你一樣的騙子。
I detest liars, like you; I believe that honesty is the best policy. = 你跟你一樣都憎恨騙子。