Commas Used in Complex Sentences.
In Punctuation Pitfalls – The Comma, Part 2 I discussed commas used in compound sentences. Since a compound sentence contains two or more independent clauses, I took the time to define and provide examples of independent clauses.
I bring this up because today I want to tackle the use of commas in complex sentences, or ones with an independent clause and at least one dependent clause.
By way of refresher, a clause is a group of words with a subject (who dun it) and a verb (what action did they do). What separates an independent clause from a dependent clause is whether or not that particular group of words can stand alone as a sentence; that is, is the thought complete?
Here are some dependent clauses:
after the game started
before her mother served dinner
if the speaker was right
when the judge finally made his ruling
because the story held my interest to the end
In each case, the group of words contains a subject and verb, but because of the conjunction that introduces the clause, the thought is incomplete. (Bonus coverage: these conjunctions are called subordinate conjunctions because they subordinate a dependent clause to the independent clause).
I love these complex sentences because the comma use is so straightforward. If the dependent clause comes first, use a comma between the two clauses. However, when the independent clause comes first, you don’t need a comma between the two.
Notice the first sentence in the above paragraph. The dependent clause because the comma use is so straightforward came after the independent clause, so no comma was necessary. However, in the next two sentences, the dependent clauses came first, so each needed a comma at the end of the dependent clause.
Here are some additional examples of dependent clauses beginning sentences, and therefore requiring commas.
Because his brother finished first, he won the prize.
Since the rain stopped, we put away our umbrellas.
If the pitcher strikes out the next batter, she will set a personal record for the season.
Here are examples of dependent clauses following independent clauses and therefore not requiring commas.
The defendant thanked his attorney after the hearing ended.
The road won’t open until Monday because the workers haven’t finished clearing away the debris.
The media attention increased when the two best skiers each moved into the semifinals.
As I said, this comma use is straightforward (read, easy). No exceptions and no judgment calls. That’s my kind of punctuation rule. 😀