Boundaries questions test punctuation between and within sentences: periods, commas, semicolons, colons, and dashes. The digital SAT is ruthless about a few specific rules — master them and these become free points.
Core test: Is each side of the punctuation an independent clause (could stand alone as a sentence) or not? That single check drives most answers.
The rules that show up constantly
- Two independent clauses need: a period, a semicolon, or a comma + FANBOYS conjunction (for, and, nor, but, or, yet, so). Never a comma alone (that's a comma splice).
- Colon — must follow a complete sentence; introduces a list, explanation, or example.
- Semicolon = works like a period. Both sides must be complete sentences.
- No punctuation between a subject and its verb, or before an essential (restrictive) phrase.
Fast trick: If the choices differ only in punctuation, mentally replace each with a period. If a period works, a semicolon works too — and a lone comma never will.