2.2 Fragments, Run-ons, and Comma Splices

Sentence Boundaries Are Editing Decisions

ACT English questions about sentence boundaries often look like punctuation questions, but the real issue is completeness. The official ACT materials describe English as revising and editing written text, and sentence structure and formation sit inside Conventions of Standard English. You are expected to decide whether the passage has a complete sentence, an incomplete piece, or two complete sentences jammed together.

The fastest route is mechanical: find the subject, find the complete verb, and test whether the thought can stand alone. Do not let length fool you. A long string of words can be a fragment, and a short sentence can be perfectly complete. The ACT often hides the boundary error inside a paragraph that sounds conversational.

What Counts as a Complete Sentence

A complete sentence has three parts:

A sentence can include extra phrases before, between, or after those core parts. Cross out interruptions to see the base sentence. The analyst, after comparing the maps from three surveys, revised the boundary line is complete because the analyst revised is the core.

Fragments: Pieces Presented as Sentences

A fragment is missing a subject, a complete verb, or a complete thought. ACT fragments often start with a dependent marker such as because, although, when, while, after, before, if, since, or unless. Although the bridge was repaired before winter has a subject and verb, but although makes the thought incomplete. It needs a main clause: Although the bridge was repaired before winter, inspectors scheduled another review.

Another common fragment uses an -ing phrase: Walking through the restored theater before the ceremony. The phrase describes an action, but it does not say who completed a main action. A complete sentence would be Walking through the restored theater before the ceremony, the director noticed that the balcony lights were still off. The noun after the introductory phrase must be the person or thing performing the action.

A third fragment looks like an added detail: A design that reduced energy use by nearly thirty percent. The phrase has useful information but no main verb. A clean revision is The team approved a design that reduced energy use by nearly thirty percent.

Run-Ons: Complete Sentences Without Boundaries

A run-on occurs when two independent clauses are fused without proper punctuation or connection. The rehearsal ended late the stage crew still reset every scene is wrong because the rehearsal ended late and the stage crew still reset every scene are both complete. They need a boundary.

Legal fixes include a period, a semicolon, a comma plus a coordinating conjunction, or a subordinating word that makes one idea dependent. Each fix changes the rhythm and sometimes the logic:

• Period: The rehearsal ended late. The stage crew still reset every scene.
• Semicolon: The rehearsal ended late; the stage crew still reset every scene.
• Comma plus conjunction: The rehearsal ended late, but the stage crew still reset every scene.
• Subordination: Although the rehearsal ended late, the stage crew still reset every scene.

The best ACT answer usually keeps the intended relationship. If the second idea contrasts with the first, but or although may beat a semicolon. If the second idea explains the first, a colon or because may be better. Grammar gets you to the finalists; context selects the winner.

Comma Splices: The Comma Trap

A comma splice joins two independent clauses with only a comma. It feels less wrong than a fused run-on because the reader sees a pause, but the grammar problem is the same. The survey closed Friday, analysts released preliminary results Monday is a comma splice. A correct version is The survey closed Friday, and analysts released preliminary results Monday or The survey closed Friday; analysts released preliminary results Monday.

ACT answer choices often include a comma splice beside a fragment. Do not choose between them by sound. Label the parts. If both sides are independent, a comma alone fails. If one side is dependent, a comma may be exactly right.

Boundary Fixes by Meaning

ACT-Style Traps

One trap is the false fix that deletes a needed subject. Because the recipe called for fresh basil and roasted tomatoes, created a bright sauce is still a fragment because created has no subject. Another trap is an answer that adds a semicolon after a dependent opener: Because the recipe called for fresh basil; the sauce tasted bright is wrong because because makes the first part dependent. A third trap is a wordy answer that avoids the comma splice but creates redundancy. Correct boundaries still need concise ACT-style prose.

When you practice, mark every underlined punctuation question with C for complete or D for dependent on each side. That small notation turns a vague editing instinct into a repeatable process.