1. What is a Complex Sentence?
A complex sentence is a sentence with an independent clause and a dependent clause. It is one of the four main types of sentence structures. In a complex sentence, the independent clause shares the main information, and the dependent clause(s) provide details. Complex sentences let us share lots of information with just one sentence.
2. Examples of Complex Sentence
In the examples below, independent clauses are orange and dependent clauses are green.
- When the dog went to the county fair, he ate popcorn.
- If the dog goes to the county fair, he will eat popcorn.
- The dog went to the county fair after he smelled popcorn.
- The dog smelled popcorn, so he went to the county fair.
As you can see, sometimes the independent clause comes first, and sometimes the dependent clause comes first.
3. Parts of Complex Sentences
All complex sentences have one independent clause and one or more dependent clauses. They often also include dependant “marker” words or coordinating conjunctions.
a. Independent Clause
An independent clause is a clause that can exist as a sentence on its own. It has a subject and a predicate and makes sense as a complete sentence. As mentioned, the independent clause shares the main information of a complex sentence.
- The dog ate popcorn.
- The dog ran quickly.
- He ate popcorn.
- He went to the county fair.
So, you can see that all of the clauses above are working sentences. All complex sentences have ONLY one independent clause.
b. Dependent (Subordinate) Clause
A dependent clause has a subject and a predicate; BUT, it can’t be a sentence. It provides extra details about the independent clause, and it doesn’t make sense on its own, like these:
- After he went to the fair
- Though he ate popcorn
- While he was at the county fair
- If the dog eats popcorn
Though all of the examples above contain subjects and predicates, none of them make sense. Each leaves an unanswered question. By itself, a dependent clause is just a fragment sentence (an incomplete sentence). So, it needs to be combined with an independent clause to be a sentence.
Complex sentences have at least one dependent clause, but they can have two or more.
c. Dependent “Marker” Words/Subordinating Conjunctions
A dependent marker word (also called a subordinating conjunction) goes at the beginning of an independent clause. It turns an independent clause into a dependant clause by adding details like time or context. Common dependent marker words include after, although, as, because, before, even if, even though, if, since, though, unless, until, whatever, when, whenever, whether, and while. Let’s start with an independent clause:
He was at the county fair = Independent clause
Now, add a dependent marker word, like “when”:
When he was at the county fair = Dependent clause
Here are some complex sentences with the marker words underlined:
- When he was at the county fair, the dog ate popcorn.
- Though he likes cotton candy, the dog loves popcorn.
- The dog gets a stomachache if he eats popcorn.
- The dog ate popcorn while he was at the county fair.
d. Coordinating Conjunctions
Coordinating conjunctions are words that connect sentences, like and, but, for, or, nor, so, and yet. If you are using a coordinating conjunction to connect an independent and a dependent clause, it needs a comma before it. Here are some examples with the conjunctions underlined:
- The dog ate popcorn, so he didn’t want dinner.
- He likes popcorn, but it has to be hot.
- The dog doesn’t like ice cream, for it is too cold.
- Pop the popcorn, and then eat it.
4. Types of Complex Sentences
A complex sentence is a type of sentence on its own, but the number of dependent clauses can vary.
a. Complex Sentences with One Dependent Clause
Many complex sentences have an independent clause and just one dependent clause, like these:
- The dog didn’t eat popcorn, nor did he eat cotton candy.
- The dog runs fast, so make sure you watch him.
- When he was at the county fair, the dog bought popcorn.
- Since the popcorn was cold, he didn’t like it.
b. Complex Sentences with More than One Dependent Clause
Complex sentences only ever have one independent clause, but they can have more than one dependent clause, like these:
- The dog didn’t eat popcorn, nor did he eat cotton candy or drink soda.
- The dog can run fast, so make sure you watch him or you will lose him.
- When he was at the county fair, the dog bought popcorn but not cotton candy.
- Since the popcorn was cold, the dog didn’t like it, so he got cotton candy.
5. How to Write a Complex Sentence
Complex sentences are very common and pretty easy to write, as long as you remember their rules. When writing a complex sentence, you should follow these important guidelines:
- All complex sentences have an independent clause and a dependent clause.
- Complex sentences can have more than one dependent clause.
- To connect independent and dependent clauses, you need dependent marker words and/or coordinating conjunctions.
- Dependent marker words come at the beginning of a complex sentence
- Coordinating conjunctions come after commas