G6: Run-on sentences

G6Run-on sentences

Run-on sentences are independent clauses that have not been joined correctly. An independent clause is a word group that can stand alone as a sentence. (See B4-a.) When two independent clauses appear in one sentence, they must be joined in one of these ways:

Recognizing run-on sentences

There are two types of run-on sentences. When a writer puts no mark of punctuation and no coordinating conjunction between independent clauses, the result is called a fused sentence.

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A far more common type of run-on sentence is the comma splice—two or more independent clauses joined with a comma but without a coordinating conjunction. In some comma splices, the comma appears alone.

comma splice Air pollution poses risks to all humans, it can be deadly for asthma sufferers.

In other comma splices, the comma is accompanied by a joining word that is not a coordinating conjunction. There are only seven coordinating conjunctions in English: and, but, or, nor, for, so, and yet.

comma splice Air pollution poses risks to all humans, however, it can be deadly for asthma sufferers.

However is a transitional expression, not a coordinating conjunction, and cannot be used with only a comma to join two independent clauses (see G6-b).

Revising run-on sentences

To revise a run-on sentence, you have four choices.

  1. Use a comma and a coordinating conjunction (and, but, or, nor, for, so, yet).

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  2. Use a semicolon (or, if appropriate, a colon or a dash). A semicolon may be used alone; it can also be accompanied by a transitional expression.

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  3. Make the clauses into separate sentences.

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  4. Restructure the sentence; try subordinating a clause.

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One of these revision techniques usually works better than the others for a particular sentence. The fourth technique, the one requiring the most extensive revision, is often the most effective.

Recognizing run-on sentences

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If you find an error, choose an effective method of revision. See G6-a to G6-d for revision strategies.