ACT sentence structure strategies
ACT English tests sentence structure across the 75-question, 45-minute section. Questions cover sentence fragments, comma splices and run-ons, and parallel structure in lists and comparisons. These strategies cover identifying whether a group of words forms a complete sentence, recognizing when two independent clauses are improperly joined, and maintaining parallel structure across coordinated elements.
The core principle
Every sentence needs a subject and a verb, and must express a complete thought. A fragment is missing one of these three. A run-on is two complete sentences joined without proper punctuation or a conjunction. Parallel structure means that items in a list or elements joined by a conjunction take the same grammatical form. A fragment might have a subject and a verb but start with a subordinating word like "although," "because," or "when" without a main clause to complete the thought. A comma splice joins two independent clauses with only a comma. The fix is to add a coordinating conjunction (and, but, or), replace the comma with a semicolon, or split into two sentences. For parallel structure, if the first item in a list is a gerund, every item must be a gerund.
The most common trap
Misidentifying a fragment because it looks long and complex
The underlined portion reads "Because the researchers had spent three years collecting data from every region of the country and had published their findings in a peer-reviewed journal." The sentence is long and contains multiple verbs, so it looks complete. It starts with "Because," a subordinating conjunction, and has no main clause. It is a fragment. The answer choices include the version that leaves it as a fragment because the test writers know students judge completeness by length. Check for a subordinating word at the start, and verify a main clause exists.
Step-by-step strategy
When to use: any underlined portion that spans a clause boundary or contains a list, a comparison, or a conjunction.
- 1Check whether the underlined portion forms a complete sentence. Find the subject and the verb. If it starts with a subordinating word, verify a main clause follows.
- 2If two independent clauses appear, check the join. A comma alone is a comma splice. The fix is a comma plus a coordinating conjunction, a semicolon, or a period.
- 3If the underlined portion contains a list or a comparison, check that every element takes the same grammatical form. Nouns pair with nouns, gerunds with gerunds, infinitives with infinitives.
- 4Read the sentence aloud in your head. If it sounds like it trails off, it is a fragment. If it runs past a natural stop, it is a run-on.
- 5Choose the answer that produces a complete, properly joined, parallel sentence. If the original is already correct, select "NO CHANGE."
When not to use: when the question tests a single word choice or punctuation rule rather than sentence-level structure.
Related pages
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