Study Guide

Sentence Boundaries

Sentence boundary questions test your ability to correctly separate or join independent clauses. You must know when to use periods, semicolons, commas, and conjunctions.

Key Rules

Two independent clauses CANNOT be joined by only a comma (comma splice).
Use a semicolon (;) to join two independent clauses without a conjunction.
Use a comma + FANBOYS (For, And, Nor, But, Or, Yet, So) to join two independent clauses.
A period fully separates two independent clauses — both must be complete sentences.
A colon (:) introduces an explanation, list, or elaboration of what came before.

Common Mistakes to Avoid

Comma splices: "It was raining, we stayed inside."
Run-on sentences: two complete thoughts with no punctuation between them.
Using a semicolon when one clause is a fragment.
Forgetting that "however" and "therefore" are NOT conjunctions — they need a semicolon before them, not just a comma.

SAT Strategy Tips

→Test each option: cover the punctuation and check if both sides are complete sentences.
→If both sides are complete sentences, you need either: period, semicolon, or comma + FANBOYS.
→"However," at the start of a sentence needs a period or semicolon before the previous sentence.
→Watch for relative clauses starting with "which," "who," or "that" — they are NOT independent clauses.

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Sentence Boundaries

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