Usage of Comma (1 of 3)－ ELISA ENGLISH's Blog 英語園地

When to use a comma?

A. Use commas to avoid confusion.

(1a) I intend to share my vacation home with my parents, Mary and Joe.

=> This means: I intend to share my vacation home with my parents. My parents’ names are Mary and Joe. I will be sharing my vacation home with both of them.

(1b) I intend to share my vacation home with my parents, Mary, and Joe.

=> This means: I intend to share my vacation home with my parents, with Mary and with Joe. So I will be sharing my vacation home with four people.

(2a) I cannot stand a hypocrite like you. I hate politics.

=> This means: You are a hypocrite. I cannot stand you.

(2b) I cannot stand a hypocrite; like you, I hate politics.

=> This means: I am like you. I cannot stand a hypocrite

(3) I like eating meat and vegetable, and fruit is her favorite.

=> This means: I like eating meat and vegetable. She likes eating fruit the most. I did not mention if I like eating fruit or not.

(4) To Cindy, Brook is nothing but a trouble.

=> This means: Brook is a trouble in the eyes of Cindy.

(5) Outside, the garden was cluttered with faded flowers.
=> Without the comma, it will mean “outside the garden” instead of “outside”, and the grammar will be inaccurate.

不用逗號，它將讓人認為那是「在花園之外」而不是「在外面」, 并且語法也是不對的。

(不用逗號正確語法: Outside the garden were clusters of faded flowers.)

See the difference!

** Without comma, they will be treated as a unit.

For Example:

(6a) For dinner, I want meatloaf, banana, macaroni, and cheese.

=> This means: I want four items prepared separately. I want cheese in addition to macaroni.

(6b) For dinner, I want meatloaf, banana, macaroni and cheese.

=> This means: macaroni and cheese is one item.

B. Use commas to separate independent clauses when they are joined by any of these seven coordinating conjunctions: and, but, for, or, nor, so, yet.

Ø I like taking my vacation in the winter, and she likes taking hers in the summer.

Ø I like going shopping, but I cannot stand the crowd.

Ø I have finished my lunch, yet I still feel hungry.

Ø I don’t agree with the result of his experiment, so I decide to do it myself.

Ø I decided to run for city mayor, for I believe that I have much to offer to the city.

Ø Mary cannot decide whether she should stay here with her family, or fly to London to join her boyfriend.

Ø Hardly can I determine which proposal to follow, nor am I capable of coming up with a more innovative one.

Ø I like eating meat and vegetable, while she likes to eat fruit. (while = but)

C. Use commas to separate three or more words, phrases, or clauses written in a series.

Ø Kevin and I started our 2 week vacation to Mount Rushmore, Rocky Mountains, and Grand Canyon.

Ø As an exchange for a trip to Legoland, our kids agreed to listen to our command, (to) show their best behaviors, and (to) do their own chores.

Ø Mary, who had a strong motive, who was prosecuted for murder, and who had been on suicide watch, was recently found not guilty.

Ø I will help you if you stop smoking, if you exercise every day, and if you promise not to drink anymore.

Ø Joanne has a most kind, sensitive, and untamed heart.

Ø Timmy kicked Jack in the butt, punched him in the face, and threw him on the ground.

Ø He ran, jumped, and shouted at the playground.

** Commas can be omitted if the independent clauses are very short and closely connected.

Note: Some writers have argued that the conjunction (and, but, or) does the same thing as a comma. However, to avoid confusion, it is best to use the comma between the last two items.

For example:

I approved the proposal and he did too.

I like dancing and he likes skating.

Note: Comma Splice Error & Run on Sentence Error

If two independent clauses are connected without a conjunction but a comma, this type of error is called “comma splice”. If two independent clauses are connection without proper punctuations or conjunctions, this type of error is called “run-on sentence”.

For example:

Comma Splice Error:

I decided to run for city mayor, I believe that I have much to offer to the city. (X)

Run-on Sentence Error:

I decided to run for city mayor I believe that I have much to offer to the city. (X)

=> Correction: add comma and conjunction

I decided to run for city mayor, for I believe that I have much to offer to the city. (O)

=> Correction: Separate it into two simple sentences.

I decided to run for city mayor. I believe that I have much to offer to the city. (O)

=> Correction: add semicolon to separate the sentence.

I decided to run for city mayor; I believe that I have much to offer to the city. (O)

D. Use a comma to separate two or more adjectives (coordinate adjectives) when the word and can be inserted between them, and when the order of the adjectives can be reversed.

For example:

Ø Joanne has a most kind, sensitive, (and) untamed heart. (coordinate)

Ø I cannot find the white sporty car. (non-coordinate)

Ø She wore a bright red, fancy skirt. (bright & red: non-coordinate, red & fancy: coordinate)

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