A sentence requires semicolons instead of commas when it contains independent clauses that are closely related but not joined by a conjunction. For example:
- Incorrect: "I have a big test tomorrow, I can't go out tonight."
- Correct: "I have a big test tomorrow; I can't go out tonight."
If you have a specific sentence in mind, please share it, and I can help you determine whether semicolons should be used instead of commas!