http://owl.english.purdue.edu/handouts/grammar/g_commaproof.html
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1. Skim
your paper, looking only for the seven coordinating conjunctions:
and, nor,
but, so, for, or, and yet
2. Stop
at each of these words to see whether there is an
independent clause (a complete sentence), on both sides of it. (For more
help, see our handout on independent
clauses.)
3. If
so, place a comma before the coordinating conjunction. Examples:
She wanted to buy a new car, but she didn't have
enough money to do so.
The wind blew fiercely, and the rain poured down.
1.
Skim your paper, stopping at every comma.
2.
See whether you have an independent clause (a
sentence) on both sides of the comma.
3.
If so, change the sentence in one of the
following ways:
¡¤
reword the sentence to change one clause into a
subordinate (or dependent)
clause (see our handout on dependent
clauses)
¡¤
add a coordinating conjunction after the comma
¡¤
replace the comma with a semicolon
¡¤
replace the comma with a period, question mark,
or exclamation point, and capitalize the first word of the second clause
comma splice: Americans speak too
rapidly, this is a common complaint by foreign visitors.
correct: Americans speak too rapidly; this is a common complaint by
foreign visitors.
correct: Foreign visitors commonly complain that Americans speak too
rapidly.
1. Skim
your paper, looking only at the first two or three words of each sentence.
2. Stop
if one of these words is a dependent marker such as while, because,
when, if, after, when, etc. (see our Commas
After Introductions).
3. If
necessary, place a comma at the end of the introductory dependent clause. Examples:
While I was writing, the phone rang.
Because the weather was bad, we decided to cancel our planned picnic.
After the last guests left the party, we had to begin cleaning the house.
1. Skim
your paper, looking only at the first word or two of each sentence.
2. Stop
if the word or phrase . . .
¡¤
ends in -ing
¡¤
is an infinitive (to + verb)
¡¤
is an introductory word (well, yes,
moreover, etc.)
3. Place
a comma at the end of the introductory phrase. Examples:
To get a good grade, you
must turn in all your homework problems.
Walking to work, Jim stopped for coffee at the diner.
Yes, I agree that the exam was difficult.
4. If
the sentence begins with a prepositional phrase (a phrase beginning with in,
at, on, between, with, etc.), place a comma after
the prepositional phrase if it is longer than three words or suggests a
distinct pause before the main clause. Examples:
On his way to work, Jim
stopped for coffee at the diner.
In those days we wrote with a pen and paper.
Across the street from the library, an old man waited for a bus.
1.
If the comma isn't necessary for clarity or
called for by a rule, get rid of it.
1.
Skim your paper, stopping only at the
coordinating conjunctions: and, or, nor, but, so,
for, or, and yet.
2.
Check to see whether there is an independent
clause (sentence) on both sides of the conjunction. If so, place a comma before
the conjunction. If not, do not place a comma before the conjunction.
disruptive comma: They bought two
pizzas, but ate only one.
correct: They bought two pizzas but ate only one.
1.
Find the subject and verb in each of your
sentences.
2.
Make sure that you have not separated the
subject from the verb with one comma. It's often all right to have a pair of
commas between a subject and verb for nonessential
clauses and phrases that might be added there, but rarely is a single comma
acceptable.
disruptive comma:
That man sitting in the train station, is the person I'm supposed to meet.
correct:
That man sitting in the train station is the person I'm supposed to meet.
1.
Skim your paper, stopping at the conjunctions.
2.
Check to see if these conjunctions link words,
phrases, or clauses written in a series.
3.
If so, place commas after each word, phrase, or
clause in the series (except the last one, as demonstrated in this sentence: no
comma after the word clause). Examples:
People who are trying to reduce saturated fat in their
diets should avoid eggs, meat, and tropical oils.
The candidate promised to lower taxes, protect the environment, reduce crime,
and end unemployment.
1.
Skim your paper, looking for a phrase or clause
in each sentence that explains or gives more information about a word or phrase
that comes before it. (See also our handout, Commas
With Nonessential Elements.)
2.
If you can delete the phrase or clause and
still keep the meaning, the phrase or clause is probably nonessential and needs
two commas, one before and one after (unless the phrase or clause is at the end
of the sentence).
3.
As an alternate test for a nonessential phrase
or clause, try saying "by the way" before it. If that seems
appropriate to the meaning, the phrase or clause is probably nonessential. To
understand the essential vs. nonessential distinction, compare the following
sentences. In the first, the clause who cheat is essential; in the
second, the clause who often cheats is nonessential.
Students who cheat
only harm themselves.
Fred, who often cheats, is just harming himself.