Sentence Boundaries
Every sentence needs a subject and a verb and must express a complete thought. Two complete sentences cannot be joined by only a comma.
The rules
- A fragment lacks a subject, a verb or a complete thought. Starting with while, because, although or which does not make a complete sentence on its own.
- A comma splice joins two sentences with a comma. Fix with a period, a semicolon, or a comma plus a conjunction.
- A run-on has no punctuation at all between two sentences.
- Fixes: period, semicolon, comma plus FANBOYS (for, and, nor, but, or, yet, so), or turn one part into a dependent clause.
Watch out: Treating a long phrase as a sentence. Length does not make a sentence. Look for the subject and the verb.
Worked example
The storm knocked out power for hours, we lit candles. How do you fix it?
- Two complete sentences are joined by only a comma.
- Add a conjunction after the comma.
- "So" shows the result.
Answer: The storm knocked out power for hours, so we lit candles.
Try it yourself
Practice questions for this skill are for signed-in students. A free account is all you need.