Complex Sentences

What is a complex sentence?

Definition:   A complex sentence is made up of an independent clause (the main clause) and one or more dependent clauses.


The INDEPENDENT CLAUSE has a subject and verb and can stand alone as a complete sentence.   It is also called a simple sentence.

Example: John wrote an amazing paragraph.


The DEPENDENT CLAUSE also has a subject and a verb, but it cannot stand alone.   There are two types of dependent clauses, those that begin with subordinating conjunctions and those that begin with relative pronouns.


When John wrote an amazing paragraph   (subordinating conjunction)

Who wrote an amazing paragraph (relative pronoun)


Examples of complex sentences:

When John wrote an amazing paragraph, he earned an A+ in the course.

John, who wrote an amazing paragraph, is very happy with his grade. 


Complex Sentences with Subordinate Conjunctions

One type of dependent clause is introduced by a word (or words) called a subordinating conjunction .   The clause does have a subject and a verb, but it begins with a subordinating conjunction .   When a clause starts with a subordinating conjunction, the clause becomes dependent—it cannot stand alone.


 List of Common Subordinate Conjunctions


after *

since *


so that

as *


as if

till *

as long as


as though

until *



before *


even though









* Remember that some of the subordinating conjunctions can also be used as prepositions.   These words have an asterisk (*) beside them.   To decide whether those words function as prepositions or subordinating conjunctions, label the sentence parts.   If only a noun or pronoun appears, the word group is a prepositional phrase. If a subject and verb appear after any of these words, the word group is a dependent clause.


PREPOSITIONAL PHRASE:   Bart has not been happy (since his accident).

DEPENDENT CLAUSE:   Bart has not been happy [since he returned home].


Access the file with a list of common subordinating conjunctions here.


When one of these subordinating conjunctions is placed before an independent clause, the clause can no longer stand by itself.   It becomes dependent.

Robert rode the bus to town. (independent clause)

When Robert rode the bus to town. (dependent clause -- cannot stand alone as a sentence)


Punctuation: Complex Sentences with Subordinate Conjunctions

When the dependent clause comes first, a comma is required. Dependent clauses are in italics.


When I read the story, I could imagine everything.


However, when the dependent clause follows an independent clause, no comma is used.


I could imagine everything when I read the story.


Watch this video explanation with examples:

Access the file here if you would like to follow along with the video or print it to take notes.



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