Grammar Smart 3rd Edition - Princeton Review 2014
D. The Comma
PART 4. Punctuation
The comma is the most abused punctuation mark, possibly because writers are sometimes so worried about following rules that they forget to pay attention to the way the words sound when spoken. Commas help a reader understand the rhythm of the sentence. If you are having comma problems, try saying your sentence out loud and listening for natural pauses. The function of a comma is to slow the reader down briefly—to make the reader pause. The omission of a comma can allow phrases and clauses to crash into one another, thereby confusing the reader.
Commas can influence the meaning of your sentence. Consider the following:
Although I wanted to kill Max, I controlled myself.
Although I wanted to kill, Max, I controlled myself.
In the first sentence Max is the person I wanted to kill; in the second sentence I am talking to Max about my desire to kill something else. The comma controls the meaning.
Let’s look at another:
The food tastes terrible, however the cook fixes it.
The food tastes terrible; however, the cook fixes it.
In the first sentence, the food tastes terrible no matter how the cook fixes it. In the second sentence, the cook improves the taste of the food. Again, the comma controls the meaning.
Rules For Commas
1. Use a comma to separate two independent clauses connected by the following: and, but, or, nor, for.
Bob was usually a quiet man, but he screamed upon entering the room.
The strange man lying under the table appeared to be dead, or just possibly he was only napping.
If the independent clauses are short, you may omit the comma.
The man was still and his foot was bleeding.
His hat was on but his pants were off.
2. Use a comma to separate elements in a list or series; the comma is a substitute for and. Some people omit the final comma, but we prefer to leave it in.
Bob tried to breathe, to keep from fainting, and to remember his first aid.
Next to the man was a bassoon, a water balloon, and a raccoon.
3. Use a comma to separate introductory phrases and clauses from the independent clause.
After catching his breath, Bob squatted next to the man and took his pulse.
When he felt nothing, Bob picked up the bassoon and blew.
Although he had never played a bassoon before, he somehow managed to make beautiful music.
If the introductory phrase is short, you may omit the comma.
After dark they stopped playing basketball.
But be careful. Always use a comma if omitting it could cause confusion.
When Bob began to eat, rats ran across the carpet.
Not: When Bob began to eat rats ran across the carpet.
Before leaving, Bob heard the man sneeze.
Not: Before leaving Bob heard the man sneeze.
4. In a series of adjectives, use a comma if the adjectives could also be separated by and.
The nimble, fat raccoon began to poke at the water balloon.
(Could write as: The nimble and fat raccoon...)
If the and doesn’t fit, leave out the comma:
The man’s white cotton shirt was balled up in a corner.
(Wouldn’t write as: The man’s white and cotton shirt.)
If this rule seems confusing, try reading the sentence aloud. If you make a slight pause between adjectives, put in commas. Otherwise, leave them out. Another test: if you can change the order of the adjectives, put in commas. For example:
The handsome, brilliant scholar
Or: The brilliant, handsome scholar
The frilly party dress
Not: The party frilly dress
5. Use commas to set off clauses, but don’t use commas for defining clauses. (Quick review: a defining, or restrictive, clause is one that can’t be left out of a sentence. Clauses that don’t define can be lifted from the sentence without changing the meaning. Also, a defining clause specifies which part of a larger group we are talking about.)
Bananas that are green taste tart. (that are green defines which bananas we mean)
Bananas, which grow in the tropics, do not need refrigeration. (which grow in the tropics refers to all bananas. The clause can be lifted from the sentence without changing the meaning.)
Let’s look at a sentence you could punctuate either way, depending on the meaning.
The men who were tired and hungry began eating sardines. (who were tired and hungry is a defining clause, telling us which men we mean)
The men, who were tired and hungry, began eating sardines. (who were tired and hungry describes all of the men, and doesn’t differentiate these men from other men who weren’t tired and hungry)
6. Words or phrases that interrupt the sentence should be set off by commas.
Now then, let’s get down to work.
“Help me,” he said, before falling down the stairs.
What the candidate promised, in fact, is impossible to achieve.
Hello, I must be going.
7. Use commas to set off an appositive. An appositive is a word or phrase that explains or introduces the noun that precedes it.
Mrs. Bowden, my favorite teacher, is wearing a hat.
Ralphie, the president of the student council, is on probation.
Remember that commas are one way to make your writing clear. Reading your sentences aloud is a very good way to find the natural place for commas, as is inspecting your sentences for ambiguity or confusion.