Roane State Community College

There are a few types of sentence structure problems that you should look for in your writing as you are editing and proofreading. These include comma splices, run-on or fused sentences, and sentence fragments. Below are some explanations of these issues and some strategies for finding and correcting them. You also might find our page covering commas helpful.

Comma Splices

One major sentence error that writers often struggle with is the comma splice. A comma splice contains two main ideas or sentences joined incorrectly with only a comma. A comma is used to create pause in a sentence and to separate the main idea from nonessential elements of the sentence. It is not a strong enough piece of punctuation to join two sentences together.

Consider this comma splice:
Joe likes eggs, Melissa likes cereal. Here we have two sentences or complete ideas that are joined only by a comma, but remember, the comma is not a strong enough punctuation mark to join two complete sentences.

Here are some corrected versions:
Joe likes eggs, but Melissa likes cereal. (Here, we have added a coordinating conjunction, or what we often call FANBOYS--for, and, nor, but, or, yet, so. A comma can only be used to join two sentences together when it is helped out by a coordinating conjunction.)

Joe likes eggs; Melissa likes cereal. (You can replace the comma with the semicolon because the semicolon is a much stronger punctuation mark. It is strong enough by itself to join two sentences together. One caution about the semicolon, though: it should only be used to join sentences that have closely related ideas, and using it too frequently can create choppiness in your writing.)

Joe likes eggs; however, Melissa likes cereal. (We can use what is called a conjunctive adverb after the semicolon if we want to more clearly show a relationship between the sentences. Conjunctive adverbs are words like however, nevertheless, consequently, as a result, therefore. Remember that a comma needs to follow the conjunctive adverb, and a semicolon should come before it as in the example above.)

Although Joe likes eggs, Melissa likes cereal. (We can use a subordinating conjunction, or a dependent word, like because, although, as, until, unless, and when to join two sentences together. Notice that in the above example we have the dependent word "although" at the beginning of the sentence. Because of this, the clause “Although Joe likes eggs” becomes a dependent clause, meaning that it cannot stand alone as a complete sentence. What we end up with, then, is one dependent clause and one independent clause, or a complete sentence. A comma is strong enough to join a dependent and independent clause together, so this comma use does not create a comma splice error.

If we wanted, we could also invert the order of these clauses to come up with this:
Melissa likes cereal although Joe likes eggs. (In this case, the dependent word is in the middle of the sentence, so no comma is needed. Commas are usually not needed in front of dependent words).

Run-on/Fused Sentences

A run-on sentence is more than one sentence joined together incorrectly. It’s called a "run-on" because it "runs on" with more than one idea. Consider this example of a run-on sentence:

I have a poor backhand I don’t play tennis well.

Do you see that two main ideas are actually stated here? 1) I have a poor backhand. 2) I don’t play tennis well. These two main ideas can’t be joined together without using appropriate punctuation. Without proper punctuation and/or a joining word, we have a run-on sentence.

Here are some examples of ways that these sentences can be joined correctly:

I have a poor backhand. I don’t play tennis well. (period added)
I have a poor backhand; I don’t play tennis well. (semicolon added)
Because I have a poor backhand, I don’t play tennis well. (subordinating conjunction or dependent word added to the beginning of the sentence with a comma between these ideas)
I don’t play tennis well because I have a poor backhand. (subordinating conjunction or dependent word as the connecting word)
I have a poor backhand, so I don’t play tennis well. (coordinating conjunction or FANBOYS and a comma added)
I have a poor backhand; therefore, I don’t play tennis well. (semicolon and conjunction)

To find run on sentences, read each of your sentences closely to figure out where one sentence ends and the new one begins. Then separate the ideas with the appropriate punctuation and/or transition word.

Sentence Fragments

Remember a group of words that begin with a capital letter and end with a period do not always make a complete sentence. Every complete sentence must have at least one subject, one verb, and must express a complete thought. If it doesn’t, it is a fragment. 
Before you can correct fragments, you have to be able to identify them. Here is more information about the three elements that a complete sentence must have:

1. a clear subject. The subject is the who or what the sentence is about.
2. a clear verb. The verb is what the who or what of the sentence does or is.
3. at least one independent clause. An independent clause is a word group consisting of a subject and verb that does not begin with a subordinating conjunction (dependent word- because, when, if, as, until, although, whenever, while) and expresses a complete thought or statement. If your sentence begins with a subordinating conjunction, be sure to add an independent clause after it to express a complete idea.

If your sentence is missing any one of these three elements, it is a fragment. Once you've identified fragments in your writing, you can more easily correct them. Most fragments can be corrected by one of two methods:

1. connecting the fragment to a nearby independent clause (complete sentence).
2. revising the sentence itself by adding the missing element (a subject or verb or both).

First check to see if you can connect your fragment to a nearby complete sentence. Many fragments can be easily corrected by connecting the fragment to the sentence either before or after it.

Example:
That summer, we had the time of our lives. Fishing in the morning hours and splashing in the lake after lunch.
That summer, we had the time of our lives, fishing in the morning hours and splashing in the lake after lunch. (Fragment is connected to the previous sentence by a comma.)

If there is no sentence to connect your fragment to, then you need to revise the fragment. Here are some guidelines for revising different types of fragments:

Dependent word fragments
Many times fragments start with a dependent word (subordinating conjunction) like because, when, if, as, until, although, whenever, while. Usually a dependent word fragment can be combined with a nearby sentence, but if it can’t, the dependent word might need to be eliminated. Here is an example:

When the candidates either disagreed about priorities or pushed for different strategies.
The candidates either disagreed about priorities or pushed for different strategies.

Phrase fragments
A phrase fragment is a fragment that lacks a subject or a complete verb – or both. Phrase fragments often begin with verbals (words that sound like verbs but aren’t) like “ing” words. Most of the time these fragments can be revised by connecting them to a nearby sentence, but if this doesn’t work, the verbal needs to be turned into a subject and verb phrase. Here are two examples of revising a phrase fragment. For example:

That summer, we had the time of our lives. Fishing in the morning hours and splashing in the lake after lunch.
That summer, we had the time of our lives. We fished in the morning hours and splashed in the lake after lunch. (Fishing is turned into subject/verb group we fished. Notice that we had to change splashing to splashed as well.)

“For example” fragments
Watch for fragments that begin with words that introduce examples. Most of the time, the missing elements (both subject and verb) need to be added. Here's an example:

Hansel and Gretel faced many dangers. For example, their cruel stepmother, the wicked witch, and the dangers of the forest. 
Hansel and Gretel faced many dangers. For example, they had to contend with their cruel stepmother, outsmart the wicked witch, and survive the dangers of the forest. (We had to supply the needed subject and verb (they had) in order for this sentence to express a complete idea.)

The best tip for finding fragments:
Read your essay out loud from end to beginning (last sentence to first). This might sound strange at first, but it really works. Reading our sentences out of logical order forces your brain to read our words out of context; this causes you to really see if what you have written expresses a complete idea.