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Basic Grammar and Punctuation: Run-on Sentences

The tutorials below address basic grammar and punctuation errors writers routinely have. Use these guidelines to proofread and correct errors in your papers before submission. For hands-on help, see a tutor in your campus Learning Support Commons.

About Run-on Sentences

If you're confused about where one idea begins and another starts, your reader will be as well. Run-on sentences are two or more complete sentences that are not combined with correct punctuation.

For example: This is my winning lottery ticket, I bought it at Publix.

HOW TO CHECK FOR RUN-ON SENTENCES:

1) Read the words between each capital and period out loud.  Do you see a subject and verb – can you determine who does what?

2) A run-on sentence has more than one subject/verb combination. It has two or more answers to who does what?

In the example: This is my winning lottery ticket, I bought it at Publix.

Sentence 1 – This is my winning lottery ticket.

Sentence 2 - I bought it at Publix.

Common run-on sentence problem #1 - the comma splice.

A comma alone is not enough to connect two sentences.

For example:

Wrong – I was tired from working late, I had to go to class anyway.

Right – I was tired from working late; I had to go to class anyway.

Right – I was tired from working late, but I had to go to class anyway.

Common run-on sentence problem #2 - the fused sentence

Sentences cannot just run together. They must be joined with a coordinating conjunction or a subordinating conjunction.

For example:

Wrong – My brother just graduated from high school he will attend St. Petersburg College.

Right – My brother just graduated from high school, so he will attend St. Petersburg College.

Right – My brother will attend St. Petersburg College because he wants to study nursing.

HOW TO FIX RUN-ON SENTENCES: 

When you see two sentences between the capital and the period, ask yourself where does the first idea end and the next begin? Are these sentences joined properly? A comma is not enough!

For example: The boy ran away hysterically, the dog chased after him barking wildly.

Sentence 1 – The boy ran away hysterically.

Sentence 2 - The dog chased after him barking wildly.

This run-on sentence is made up of two sentences and should be punctuated as follows:

1) Two simple sentences: The boy ran. The dog chased.

2) A compound sentence: The boy ran, and the dog chased.

3) A complex sentence: The boy ran because the dog chased.  

The simple solution for run-on sentences:

1) Read the words between each capital and period out loud.  Do you see a subject and verb – can you determine who does what?

2) Separate each subject and verb with a period into two simple sentences.

Wrong – The singer bowed the crowd grew still.

Right – The singer bowed. The crowd grew still.

Some students think they have to write complicated sentences, but separating ideas into simple sentences can add clarity to your writing and is better than writing a run-on.

Another solution for run-on sentences:

Using only simple sentences can make your writing sound choppy, so use compound sentences to join related ideas with a semi colon or a coordinating conjunction.

Wrong – The weather was nice, we went to the beach!

Right – The weather was nice; we went to the beach!

Right – The weather was nice, so we went to the beach!

Use complex sentences to show the relationship between ideas with a subordinating conjunction.

Wrong – We had pizza for dinner we couldn't decide what to cook.

Right – We had pizza for dinner because we couldn't decide what to cook.

Wrong – It was a holiday, we went to the park.
Right – Since it was a holiday, we went to the park.

Note how the punctuation changes depending on whether the subordinate clause comes at the beginning (with a comma) or end (without a comma) of the sentence.