In English, sentences are classified into four basic structures: Simple, Compound, Complex, and Compound-Complex. Learning the nuances of each of these structures will help add variety to your writing.
These four basic sentence structures are based on the use of dependent and independent clauses in a sentence, so first, we need to understand how these clauses work.
A dependent clause is not a complete sentence, and does not express a complete thought. A dependent clause can, however, contain a subject and a verb, but it cannot stand alone as a sentence, as in the examples below:
When the semester was over.
Because she stayed up all night.
When they went to the movies.
As you can see, these sentences do not represent a complete thought; they are dependent on other words to complete the sentence.
An independent clause can stand alone as a sentence. It expresses a complete thought and needs no other words to complete it. It will always have a subject and a verb, as in the examples below:
The snow fell all day long.
The dog jumped the fence.
The college closed for the summer.
Even very short sentences can be independent clauses or complete sentences, as long as a subject and verb are present:
The snow fell.
The dog jumped.
The college closed.
Consequently, very long sentences (or what appear to be sentences) can still be dependent clauses:
Although the rain fell all morning and into the night as the thunder rolled across the hillside.
While the car sped out of control during the rain-delayed race at Sunset Hills Speedway.
Beginning with the final play of the half when the quarterback was carted off the field after he was tackled.
Each of the previous sentences, even though quite long, are dependent clauses and need other words to form a complete sentence.
Now that we understand clauses, let’s look at our four sentence structures.
A simple sentence contains one independent clause and no dependent clause.
I eat blueberry muffins.
My uncle sold his old Ford pickup.
School has been cancelled due to the snow storm.
A compound sentence contains two or more independent clauses, but no dependent clauses. The clauses are joined by a conjunction (or coordinating conjunction).
S V S V
He cooked dinner, and she cleaned up.
“He cooked dinner” is a complete thought or sentence, with a subject and verb. “She cleaned up” is also a complete sentence with a subject and verb. The coordinating conjunction, “and” joins the two independent clauses together to form a compound sentence. Below are other examples of compound sentences.
The screaming children frightened the pelicans, and they flew away.
Winter is almost over, and spring isn’t far behind.
Joe quit his job, but he found a new one.
Complex sentences are a bit more – complex. These sentence types have one independent clause (I) and at least one dependent clause (D). The dependent clauses are italicized:
After John couldn’t find a job, he realized he should go back to school.
While away on vacation, the neighbor’s house was burglarized.
Since Lisa was absent from class, she had to make up the exam on Monday.
A compound-complex sentence has multiple independent clauses and at least one dependent clause. The dependent clause is introduced by either a subordinate conjunction (such as while, although, or because) or a relative pronoun (such as who
Below, the independent clauses are underlined, and the dependent clauses are in red.
Catch-22 is widely regarded as Joseph Heller’s best novel, and because Heller served in World War II, which the novel satirizes, the zany but savage wit of the novel packs an extra punch. (example from Purdue Owl)
Because I am a writing tutor, some people expect me to write perfectly without fail, but that is unrealistic.
Although I love reading, I don’t like romance novels, although some can be entertaining.
When a dependent clause begins a sentence, a comma will follow at the end of the clause, before the independent clause. Also, a comma should be placed after an independent clause if followed by a dependent clause, as in the third example.
For English language learners and beginning writers, it is important to learn how to formulate simple sentence structures first, and then begin to incorporate more complex structures to add variety to your writing.
The ability to identify and understand different types of clauses and sentence categories will not only help you punctuate sentences properly, but will also improve your writing style.