Common Sentence-Level Errors

Run-On
A run-on or fused sentence is two independent clauses that are not separated by any punctuation.
Run-on:   Wearing a seatbelt is not just a good idea it’s the law.

Revision:  Wearing a seatbelt is not just a good idea; it’s the law.
Even if one or both of the fused sentences contain internal punctuation, the sentence is still a run-on.
Comma Splice
A comma splice is the unjustifiable use of only a comma to combine two separate sentences. One should use either a period, a semicolon, or a coordinating conjunction and a comma to separate the two statements. )
Comma splice:  Wearing a seatbelt is not just a good idea, it’s the law.
Revision:          Wearing a seatbelt is not just a good idea; it’s the law.
Both run-on sentences and comma splices may be corrected in any of the following ways:
Run-on:            Tevon won the award he had the highest score.
Comma splice:  Tevon won the award, he had the highest score.

Separate the sentences with a period. Tevon won the award. He had the highest score.
Separate the sentences with a comma and a coordinating conjunction (for, and, nor, but, or, yet, and so).

Tevon won the award, for he had the highest score.

Separate the sentences with a semicolon.

Tevon won the award; he had the highest score. If a conjunctive adverb like therefore, however, then, or consequently separates the two sentences, use a semicolon also.
I was unwilling to testify; however, I did it anyway.

Separate the sentences with a subordinating conjunction such as although, because, since, or if. Tevon won the award because he had the highest score.

Sentence Fragment
A fragment is an incomplete construction that may or may not have a subject and a verb. Specifically, a fragment is a group of words pretending to be a sentence. That group of words may be:

A phrase
A dependent Clause

1.
Fragment:   Traffic was stalled for ten miles on the freeway. Because repairs were being made on potholes.
Revision:     Traffic was stalled for ten miles on the freeway because repairs were being made on potholes.
2.
Fragment:   It was an excellent movie; one that was nominated for an Oscar.
Fragment:   It was an excellent movie. One that was nominated for an Oscar.
Revision:     It was an excellent movie, one that was nominated for an Oscar.
3.
Fragment:   Prospectors invaded the newly discovered territory. Some in wagons, some on horseback, and a few in heavily laden canoes.
Fragment:   Prospectors invaded the newly discovered territory; some in wagons, some on horseback, and a few in heavily laden canoes.
Revision:     Prospectors invaded the newly discovered territory, some in wagons, some on horseback, and a few in heavily laden canoes.
Note
The above explanations coincide very well with Bedford’s explanations in Chapters 19 and 20. Please use this handout along with the above chapters in your Bedford Handbook as guides in studying for the quizzes and in eliminating fragments, run-ons, and comma splices from your sentences.