Sentence boundaries, fragments, and run-ons: identifying a complete sentence (a subject and a verb expressing a complete thought), recognizing sentence fragments, run-on sentences, and comma splices, and fixing each with correct punctuation, a conjunction, or restructuring, on the Virginia EOC Writing test.

What this skill is asking

A complete sentence has a subject and a verb and expresses a complete thought, and the Virginia EOC Writing test asks you to tell complete sentences from fragments (incomplete) and from run-ons and comma splices (two sentences wrongly joined), and to fix each correctly. The EOC tests this with "which is a complete sentence" and "how should this be corrected" items, and sentence-boundary control is scored on the Short Paper's Usage and Mechanics domain. The skill is recognizing the boundary of a sentence and using the right tool, a period, semicolon, conjunction, or restructuring, to mark it. This page covers fragments, run-ons, comma splices, and the correct fixes.

Complete sentences and fragments

A sentence must be able to stand on its own.

The test for a fragment is whether the words express a complete thought on their own. "Because the storm hit" leaves you waiting for what happened; it is a fragment until joined to an independent clause ("Because the storm hit, the lights went out"). Watch the subordinating words, because they are the usual cause of fragments: they make a clause dependent, so it cannot stand alone. Fix a fragment by adding the missing subject or verb, or by attaching it to a complete sentence.

Run-ons and comma splices

The key recognition is that a comma alone cannot join two independent clauses, this is the single most-tested boundary rule. If both sides of a comma could stand as their own sentence, a comma is not enough; you need a period, a semicolon, or a comma with a coordinating conjunction (the FANBOYS: for, and, nor, but, or, yet, so). This also connects to sentence variety: combining choppy sentences is good style, but the combination must avoid creating a comma splice, which is why combining and boundaries are studied together.

A routine for boundary errors

Try this

Q1. What are the three things a complete sentence must have? [Recall]

• Cue. A subject, a verb, and a complete thought. A group of words missing any of these (or a dependent clause that cannot stand alone) is a fragment.

Q2. How can you correct the comma splice "The road was icy, the cars slowed down" in two different ways? [Short explanation]

• Cue. Use a semicolon ("The road was icy; the cars slowed down") or a comma plus a coordinating conjunction ("The road was icy, so the cars slowed down"). A period ("The road was icy. The cars slowed down") or subordination ("Because the road was icy, the cars slowed down") also work; a comma alone does not.