English: Usage & Mechanics for the ACT Exam

Common failure modes

These are the patterns that cause most candidates to lose marks on this topic. Recognising them in advance is half the work.

• !Inserting commas by feel ("where I would pause while reading") rather than by rule — ACT tests specific comma rules, not ear-based punctuation
• !Confusing "its" (possessive) with "it's" (it is) — this appears on virtually every ACT English section
• !Misidentifying run-on sentences: two independent clauses joined only by a comma constitute a comma splice, not a grammatically correct sentence
• !Not checking subject-verb agreement when a prepositional phrase separates the subject from the verb ("The results of the experiment [is/are]...")

Study tips

• 1Learn the six ACT-tested comma rules: (1) with introductory elements, (2) with non-restrictive clauses, (3) with coordinate adjectives, (4) with items in a series, (5) with coordinating conjunctions between independent clauses, (6) NOT between a subject and its verb.
• 2Memorize the semicolon rule: a semicolon can only join two independent clauses. If either side is not an independent clause, the semicolon is incorrect.
• 3For pronoun questions, always identify the antecedent before selecting a pronoun. The antecedent must be clear, specific, and grammatically agree in number and gender.
• 4Practice 20 sentence-structure questions targeting run-ons, comma splices, and fragments — these three error types together account for roughly 15% of English section questions.

Sample ACT English: Usage & Mechanics questions

These sample items mirror the format and difficulty of real ACT questions. Practice with thousands more on the free Koydo question bank.

1. 1

   Choose the option that best corrects the underlined portion: "The committee, which consists of twelve members agreed to postpone the vote."

   • Amembers, agreedCorrect
   • Bmembers; agreed
   • Cmembers agreed (no change)
   • Dmembers — agreed
   Why this answer?

   "Which consists of twelve members" is a non-restrictive relative clause — it provides extra information but is not essential to the meaning of the sentence. Non-restrictive clauses must be set off by commas on both sides. The clause opens after "committee," so it should close with a comma before "agreed." Option A is correct. (Illustrative.)

2. 2

   Which of the following correctly uses a semicolon? Choose the version that is grammatically correct.

   • AShe studied for three hours; but still failed the test.
   • BThe results were surprising; the treatment had no measurable effect.Correct
   • CAfter finishing the experiment; the team wrote up the results.
   • DHe was tired; and hungry after the long hike.
   Why this answer?

   A semicolon can only join two independent clauses. In option B, "The results were surprising" is an independent clause, and "the treatment had no measurable effect" is also an independent clause — a semicolon correctly joins them. Options A and D use semicolons before coordinating conjunctions (but, and), which is incorrect. Option C places a semicolon after a subordinate phrase, not an independent clause.

3. 3

   Select the correct verb form: "Neither the teachers nor the principal [is/are] responsible for the scheduling error."

   • AisCorrect
   • Bare
   • Cwere
   • Dhas been
   Why this answer?

   With "neither...nor" constructions, the verb agrees with the subject closest to it (the proximity rule). The subject closest to the verb is "principal" (singular), so the correct verb is "is." If the construction were reversed ("Neither the principal nor the teachers"), the correct verb would be "are."

4. 4

   Which sentence contains a dangling modifier?

   • ARunning down the street, the bus was missed by Maria.Correct
   • BHaving finished the report, she submitted it immediately.
   • CWalking to school, Jamie found a lost dog.
   • DTo prepare for the exam, students should review their notes.
   Why this answer?

   "Running down the street" is a participial phrase that must modify the subject of the main clause. In option A, the subject of the main clause is "the bus" — but the bus is not running down the street. This is a dangling modifier. In options B, C, and D, the participial phrase correctly modifies the sentence's subject.