A complex sentence consists of an independent clause
connected to a dependent (subordinate) clause. Complex sentences are useful in
writing because they can provide meaningful transitions between ideas in one
sentence.
Just as in a compound sentence, the clauses in a complex
sentence should have a useful relationship with each other. It does not make
sense to join two random clauses together just to create a complex sentence.
Consider the following examples:
Even though karate was Abigail’s
favorite sport, she spent a lot of time playing other sports.
I heard my dogs barking furiously
before the earthquake struck.
In the first example, the dependent clause, “Even
though…favorite sport” comes before the independent clause, “she spent…other
sports.” These two clauses are related because they are both describing the
sports that Abigail plays; they are connected by the subordinate conjunction
“even though” and a comma (the subordinating conjunction may not be between the
two clauses, but it still connects them).
In the second example, the dependent clause, “before the
earthquake struck”, comes after the independent clause, “I heard my dogs
barking furiously”. These two clauses are related because they both relate
scenes from the same event; they are connected by the subordinating conjunction
“before”.
There are a few punctuation rules that you need to follow
when placing dependent clauses in complex sentences.
·
When the dependent clause comes before the independent clause, it
can be thought of as an introductory clause; this usually requires a comma
after the dependent clause. The comma separates the dependent clause from the
independent clause. For example:
Once the vaccination is ready, it will
be distributed to the hospitals around the world.
In this example,
a comma follows the introductory dependent clause “Once the vaccination is
ready”, separating it from the independent clause.
·
When the dependent clause comes after the independent clause, it
does not require a comma before it. For example:
The vaccination will be distributed to
hospitals around the world once it is ready.
Here, since the dependent clause “once it
is ready” follows the independent clause, no comma is necessary.
·
When the dependent clause comes in between the independent
clause, use commas depending on if the dependent clause is necessary to the
meaning of the sentence. For example:
The vaccination that is ready will be
distributed to hospitals around the world.
The vaccination, which is now ready, will
be distributed to hospitals around the world.
In the first example, the dependent
clause is necessary to the meaning of the sentence; therefore, it doesn’t
require commas to separate it from the independent clause.
In the second example, the dependent
clause is not necessary to the meaning of the sentence, so it does require
commas to separate it from the independent clause.
Notice that the meanings of the two
example sentences are not the same. For more information on the usage of “that”
and “which”, see the “Pronouns” section of “Parts of Speech”