Email Grammar and Style: Using Commas
I. Restrictive vs. Nonrestrictive modifiers:
A modifier can be
A) a subordinate clause (i.e., a relative clause
beginning with "who," "which," "that"),
B) a coordinate modifier (a noun phrase, a verb
C) an appositive (noun).
A modifier is
- restrictive if the noun it modifies cannot be identified
without it and the sentence does not make sense unless the
identity of the noun is specified.
- 2) nonrestrictive if the modifier can be removed
without injuring the sentence.
- If the modifier is restrictive, no commas are needed.
- If the modifier is nonrestrictive, do use commas.
1) Other houses which were designed by Frank Lloyd Wright
can be seen in Oak Park.
2) The Robie House, which was designed by Frank Lloyd Wright,
can be seen in Oak Park.
1) The man towering over the others is my uncle.
2) My uncle, towering over all of us, saw the parade.
1) His first wife Jamie had blonde hair.
2) His first wife, the blonde, was named Jamie.
1) Nathaniel Hawthorne's story "The Birthmark"
provokes interesting discussions.
2) In "The Birthmark," the main character, Aylmer,
experiments on his wife Georgiana.
II. Coordination vs. Subordination:
A. Coordination joins two independent clauses with a comma
and "and, but, or, nor, so, yet." Two coordinated
independent clauses make up a compound sentence. Each clause
is equally emphasized by the grammar.
Coordinate modifiers, verb phrases and noun phrases, are dependent
clauses joined to the main clause by a comma alone; the relationship
between the modifier and the main clause is unspecified:
The early Benedictine monks revived agriculture after the
collapse of the Roman Empire, recolonizing the land that was
deserted, reintroducing industrial techniques that had been
Paying close attention to Louisa's reactions, the psychologist
made careful notes during each session.
B. Subordination, joining a dependent clause introduced by
"although, because, by, in order to, since, after"
or any relative pronoun, "who, whose, whom, which, that"
to an independent clause, creates a hierarchy among elements
of the sentence and orders experience according to some kind
of relationship between them.
By recolonizing the land that was deserted and by reintroducing
industrial techniques, the early Benedictine monks revived
The psychologist made careful notes during each session by
paying close attention to Louisa's reactions.
Rules for punctuating:
A. Place a comma before a coordinating conjunction joining
two independent clauses.
B. Commas set off a modifying clause depending upon whether
the modifier is restrictive or nonrestrictive.
The man who towers above everyone is my uncle.
My uncle, who towers above everyone, is a nerd.
(Rule:) Place a comma after an introductory subordinate
clause; subordinate clauses which follow the main clause do
not need to be introduced by a comma unless (Exception:)
the subordinating connector functions like a coordinating connector.
R: Although there are many trial marriages, there
is no such thing as a trial child.
R: Because there are so many divorces, children suffer.
Children suffer because there are so many divorces.
E: There is no such thing as a trial child, though
there are many trial marriages.
E: The supervisor decided to use the new calculator,
although she had never used it on a small job.
R: Even though the supervisor had never used it on
a small job, she decided to use the new calculator.
R: The supervisor decided to use the new calculator
even though she had never tried it on a small job.