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.
Dependent Clause:
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.
Independent Clause:
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.
Simple Sentence
A simple sentence contains one independent clause and no dependent clause.
S V
I eat blueberry muffins.
S V
My uncle sold his old Ford pickup.
S V
School has been cancelled due to the snow storm.
Compound Sentence
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 Sentence
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:
D I
After John couldn’t find a job, he realized he should go back to school.
D I
While away on vacation, the neighbor’s house was burglarized.
D I
Since Lisa was absent from class, she had to make up the exam on Monday.
Compound-Complex Sentence
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
or which).
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.
WRITING CENTER UNDERGROUND 
Hello,
I am not one of the students of this college, but I am a Native English speaker from the United States, specifically Florida, and I have a degree in Linguistics and I plan on getting my masters in the same field. I stumbled on your website and I liked the way that you explained the sentences. Having said that, I have stumbled on this book, Words on Words: A Dictionary for Writers and Others who Care about Words by the late John Brenner, a couple of years ago at the library of my alma mater: Florida Atlantic University. In a section of his book, he classifies five types of the sentences(the four we know): simple, compound, complex, compound-complex, and complex-complex sentence. That being said, I am happy to say that I now own a copy of the book, Words on Words written by the late John B. Bremner, which was extremely extremely affordable. I love his entry on sentences that I have decided to put the whole entry(including complex-complex sentence) here below and see what you think of it.This topic should be discussed, shared or spread in the grammar and linguistic communities and/or circles because I do believe that the late John Bremner has a very compelling case in introducing a complex-complex sentence. I say this because I have seen evidences of these types of sentences in books. I have always wanted to construct sentences like these. It is good to know that there is a name for such construction. It is safe to say that John Bremner was the only one(so far) to have identified it, described it and put it in his book. Almost all grammarians and linguists are not aware of this sentence construction or type. I can attest to that. Also, it does shed light on the fact that there is so much to learn about the grammar of the English language or any languages for that matter. I love it!!!
From John Bremner’s book:
Sentences
A sentence is a grammatical unit that conveys a complete thought and contains a subject and a predicate, either or both of which may be understated but understood. Sentences are principally classified as simple, compound, complex, compound-complex, complex-complex. Thus:
-A simple sentence consists of one independent clause: “He knows almost nothing.”
-A compound sentence consists of two or more independent clauses connected by a coordinating conjunction: “He knows almost nothing and he doesn’t want to study.” and “He knows almost nothing and he doesn’t want to study but he may change.”
-A complex sentence consists of an independent clause and one or more dependent clauses: “He knows almost nothing because he refuses to study.” and “Because he refuses to study, he doesn’t know he should.”
-A compound-complex sentence consists of two or independent clauses and one or more dependent clauses: “He knows that he should study but he doesn’t want to.” and “He knows that he should study but he doesn’t think that he has a chance of passing.”
-A complex-complex sentence consists of an independent clause and a dependent clause that is subordinate to another dependent clause: “He got mad when I told him that he should study.”
Before I had this book in my possession, I attempted to create a complex-complex sentence and here is what I came up with: “Now, the popular kids were pursuing those that once pursued them that they had rejected in the past.”
I ran this sentence by people who are grammar experts like you, Nancy Sullivan, who is the author of Essential Grammar, who said that the second dependent clause of my sentence”that they had rejected in the past” was awkward because she was trying to figure out which clause it was modifying. She created her own version: “Now, the boy was buying cars that needed parts that were difficult to find.”
And Diane Larsen-Freeman, who is one of the co-authors of the book, The Grammar Book. She too constructed her on her own complex-complex sentence: “The thief stole the car that was parked near the stadium where the World Series is being played.
I also saw another example of a complex-complex sentence from a forum: “The man who saw the horse that was grazing in the field was sitting on the fence that enclosed the farm.”
I want to know what you think of this and is it possible for you to create your own complex-complex sentence(s) based on your understanding of it?
What about a complex-complex in the negative, interrogative, imperative, and exclamative?
What would be the punctuation patterns for complex-complex sentences?
What about variations of a complex-complex sentence based on the definition of a complex-complex sentence(thanks to John Brenner)?:
-Independent clause with multiple dependent clauses subordinate to another dependent clause
-Independent clause with dependent clause subordinate to other multiple dependent clauses
-Independent clause with multiple dependent clauses subordinate to their own dependent clause
-Independent clause with multiple dependent clauses subordinate to their own dependent clauses
Diane Larsen-Freeman did mentioned that Nancy Sullivan’s sentence contains two relative clauses in a row. How about a complex-complex sentence containing and independent clause and?:
-two noun clauses in a row(noun clause + noun clause)
-two adverbial clauses in a row(adverbial clause + adverbial clause)
-a relative clause and a noun clause(relative clause + noun clause)
-a noun clause and an adverbial clause(noun clause + adverbial clause)
-an adverbial and a relative clause(adverbial clause + relative clause)
By the way, speaking of sentences, is sentence “type” associated with structure(simple, compound, complex, etc)? Is sentence “kind” associated with purpose(declarative, interrogative, imperative, exclamative, etc)? Or can both “type” and “kind” be used interchangeably? There is some confusion with the terminology.
Sorry for the barrage of questions! I just love sentences. Also, feel free to share this with other people.
Let me know what you think. I hope to hear from you.
Thank You,
Caleb Joseph
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Hi Caleb-
I agree with Nancy Sullivan, that the second part of the sentence is a bit awkward. We have a linguistics expert on staff, and I have forwarded your questions to her for a more thoughtful response than I might give. She is excited to respond – also a linguistics nerd, but as we are at the end of our term here, it might take some time. Thanks for visiting Writing Center Underground & good luck in the future!
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Hello E. Mack-
Thank you for responding. Sure, I cannot wait to hear her answer on the subject. I look forward to it. You’re welcome about my visiting your website. By the way, I notice that you used the dash instead of a comma or a colon(if this was formal). I decided to do the same. I had asked a professor one time when I noticed she did the same thing that you and she told me that the use of dash in this situation is very informal, which I had somewhat already known. What is your take on this use? Let me know what you think.
Best wishes,
Caleb
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