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Sentence Structure

On this page, you’ll find explanations of sentence types, along with examples of some common issues with sentence structure.

What is a sentence?
The Four Sentence Types
Common Sentence Errors
Grammar Resources
Come to the RWC
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Key Definitions

In its basic form, a sentence consists of a subject (an actor), a verb (an action) and often includes an object (something that receives the action).

Example: Sven chops wood.

  • Subject = Sven
  • Verb = chops
  • Object = wood
Independent Clauses

Sentences are made up of independent clauses, which include a subject and a verb and can stand as sentences on their own, and dependent clauses, which lack either a subject or a verb and need to be tied to an independent clause.

Independent clause: Sentences are made up of independent clauses. [This independent clause is a complete sentence.]

Dependent clause: Sentences may include a dependent clause, which is an incomplete sentence that, in many cases, adds additional information to the main idea.

  • Example: Looking at the clock, I wondered when class would end.
Diagram for sentence structure: cartoon image of girl next to apple with the sentence to the right "The girl ate an apple" with text beneath that says, "Simple: One Independent clause." Under that section is the image of a girl with an apple repeated, and then a plus sign next to a cartoon boy with an ice cream cone, with text saying, "The girl ate an apple and the boy ate ice cream," with a description "Compound: two independent clauses."

Simple Sentences

A simple sentence is comprised of a single independent clause.

  • Example: “I like Star Wars.”

"I" is the subject, "like" is the verb, and Star Wars is the "object." Even more simply, a sentence like, “I am,” is also a complete sentence, with only a subject and verb.

Compound Sentences

A compound sentence is made up of two independent clauses joined by a conjunction.

  • Example: “I watch movies, and I eat popcorn.”

This sentence is made up of two independent clauses: “I watch movies” conjoined with “I eat popcorn”, using the conjunction “and.” Without the “and.” both of these sentences could stand on their own. (But they can’t be joined together without a conjunction!)

Complex Sentences

A complex sentence is comprised of one independent clause and one dependent clause. When you encounter these, think of it like the dependent clause depends on the independent clause to make sense.

Diagram sentence structure part 2: cartoon girl next to apple is next to cartoon boy next to ice cream cone, with an arrow that points to a basketball. The cartoon boy and girl are shown to be a dependent clause that reads "After they finish eating", with the basketball shown to be the independent clause that reads, "they went outside to play. Under this is the sentence, "Complex: At least one dependent clause and one independent clause." On the second half, the basketball is next to a clock, and an arrow points from those objects to a house and a plus sign to z's. The basketball and clock are shown to be the dependent clause that reads "After playing awhile," and the house and z's are shown to be a compound sentence that reads, "they came inside and they went to sleep." Under this section is the sentence, "Compound-complex: At least one dependent clause and one complex sentence."

  • Example: “Because I ran, I’m tired.”

“I’m tired,” is an independent clause with a complete subject and verb, and can stand on its own. However, “because I ran” is an dependent clause because of the “because”–if it were only “I ran,” that would be an independent clause. As it stands with the “because,” it needs another clause to make sense.

Compound-Complex Sentences

A compound-complex sentence is made up of two or more independent clauses, and one dependent clause.

  • Example: “As soon as the movie came to theaters, I bought tickets, and I started calling up my friends.”

This sentence starts off with a dependent clause, “As soon as the movie came to theaters,” and is followed by the independent clauses “I bought tickets” and “I started calling up my friends,” joined by a conjunction. Either of the last two clauses can stand on their own, but the first clause needs one of the clauses that follows to be complete.

Not all compound-complex sentences start off with a dependent clause—it could be included in the middle of the two independent clauses, or following both of them. The most important principle, though, is that a dependent clause is connected to some other kind of clause.

As we begin to write sentences, we may fall into certain grammar traps. These may include issues like run-on sentences and sentence fragments, but may also run into other issues like misplaced modifiers and comma splices.

Run-on sentences

A run-on sentence contains two or more complete sentences that should be separated by conjunctions or punctuation but are not.

  • Example: "In my dream I’m in the van with Cosmo and we’re driving through a field of corn we’re just driving and I’m sitting there thinking 'I hope the crop does well this year.'"

To fix a run on sentence, simply separate the clauses with punctuation and/or conjunctions.

Correct: In my dream, I’m in the van with Cosmo, and we’re driving through a field of corn. We’re just driving, and I’m sitting there thinking, “I hope the crop does well this year.”


Fragments are incomplete sentences—they’re missing either a subject, a verb, or some other information that keeps them from being a complete thought. For some kinds of writing, they can be used intentionally to enhance style and help make a point, but most academic writing requires full sentences. Generally, in academic settings, fragments happen accidently and are perceived as incorrect or sloppy.

  • Example: "For some kinds of writing." [This fragment (the explanatory sentence from above) contains a subject but no verb, making the thought an incomplete fragment.]

Correct: For some kinds of writing, they can be used intentionally. [This fragment needed to be attached to an independent sentence. “They can be used intentionally” is an independent clause and is a complete sentence by itself.]

Comma splices

When two complete sentences are separated by only a comma, a comma splice occurs. Full sentences need to be ended by periods, semicolons, or colons.

  • Example: "I sat on the chair, I had an epiphany."

Correct: I sat on the chair. I had an epiphany. OR I sat on the chair, and I had an epiphany.

Misplaced/dangling modifiers

Modifiers provide more information about the sentence but are not essential to the main clause. Because of their dependent nature, modifiers can sometimes be put in the wrong part of the sentence, which results in the modifier modifying the wrong thing. Misplace modifiers at the beginning of a sentence are called dangling modifiers.

  • Example: "The man walked down the plane aisle wearing his tourist clothes."

This sentence is telling us that the aisle is wearing the man’s tourist clothes.

Correct: The man, wearing his tourist clothes, walked down the plane aisle.

  • Example: "After walking for two miles in the hot sun, the air conditioning was a welcome relief."

This sentence is saying that the air conditioning walked for two miles in the hot sun.

Correct: After Alice walked for two miles in the hot sun, she was relieved to feel the air conditioning.


Parallel structure can also be considered an issue of style, but lack of parallel structure is often disruptive enough that it feels more like a grammar error. It’s noticed most often in lists or in pairs. The basis of parallel structure is that the grammatical structure of adjacent phrases or clauses match each other.

  • "I love to paint but not drawing."

Here, the first item "to paint" is an infinitive verb, but drawing ends with “-ing,” giving the sentence an unbalanced—an unparallel—feeling

Correct: I love to paint but not to draw. --OR-- I love painting but not drawing.

Sentence Structure.mp4


Grammar, Punctuation, & Usage

Need help with grammar? Check out these resources!
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Are you ready to talk to one of our consultants about the structure of your sentences? If so, consider these questions as you prepare for a consultation:

  • What are the issues that I know I need to improve?
  • Have I read my paper out loud, slowly, to check for odd wording, verboseness, or other structural issues?
  • Are there any particular sentences that don’t seem to clearly communicate what I want them to?