Need-to-know Grammar: Run-On Sentences

A run-on sentence contains two or more independent clauses that are not connected by the proper punctuation. A run-on sentence may have a period as its only punctuation mark, or it may be inappropriately punctuated with one or more commas (this type of run-on sentence is called a "comma splice.")

The college entrance examinations will test your ability to identify and correct run-on sentences. Furthermore, you should be aware of the different ways to combine and separate independent clauses so that your writing is effective, clear, and concise.

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This is a run-on sentence:

I can't wait to go to the concert my favorite band is playing.

The sentence contains two independent clauses that run into each other:

1. "I can't wait to go to the concert"
2. "my favorite band is playing"

These are the different ways to correct the error:

1. Use a period to separate the independent clauses into sentences.

I can't wait to go to the concert. My favorite band is playing.

2. Use a semicolon to separate the independent clauses within a single sentence. A semicolon can be used alone, or it can be followed by a conjunctive adverb and a comma. (You may need to restructure the sentence when using a conjunctive adverb to maintain the clarity of the sentence.)

• conjunctive adverbs: also, consequently, furthermore, however, indeed, instead, likewise, meanwhile, nevertheless, nonetheless, otherwise, therefore, thus

I can't wait to go to the concert; my favorite band is playing.

My favorite band is playing; consequently, I can't wait to go to the concert.

3. Use a conjunction to join the two clauses. Depending on the context, use either a coordinating conjunction and a comma or a subordinating conjunction alone. (If you choose to restructure the sentence and place the subordinate clause first, use a comma to separate it from the main clause.)

• coordinating conjunctions: for, and, nor, but, or, yet, so (mnemonic = FANBOYS)
• subordinating conjunctions: e.g., after, although, as, because, before, if, since, that, though, unless, until 

I can't wait to go to the concert, for my favorite band is playing.

I can't wait to go to the concert because my favorite band is playing.

Since my favorite band is playing, I can't wait to go to the concert.

4. Change the syntax to create a compound subject, verb, or object.

I can't wait to go to the concert and see my favorite band.

This syntax creates a compound object with two infinitive phrases: "to go to the concert" and "(to) see my favorite band."

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This is a comma splice:

I am going to the concert, my sister is also going.

This sentence contains two independent clauses incorrectly separated by a comma:

1. "I am going to the concert"
2. "my sister is also going"

Correct the sentence using one of the four techniques:

1. Use a period:

I am going to the concert. My sister is also going.

2. Use a semicolon:

I am going to the concert; my sister is also going.

I am going to the concert; likewise, my sister is going.

3. Use a conjunction:

I am going to the concert, and my sister is also going.

4. Change the syntax:

My sister and I are going to the concert.

This sentence combines the two clauses by creating a compound subject ("my sister and I") and changing the number of the verb.

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• Use this quiz to test your ability to identify run-on sentences. The quiz also includes questions about sentence fragments.
• Take these interactive quizzes on run-on sentences and comma splices: 1, 2, 3, 4
• If you have trouble with any of the questions, post a comment and we will try to explain the error to you.

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