ACT English: Sentence Structure (Drill 1)

Question 1. Which choice makes the sentence most grammatically acceptable?

• A) No Change (Having trained for six months, the marathon route seemed manageable), as the sentence presents it
• B) Having trained for six months, the young runner found the marathon route manageable ✓
• C) Having been trained for six months, the marathon route was manageable
• D) After six months of training, the marathon route seemed manageable to her

Explanation: Choice B is correct. The opening participial phrase "Having trained for six months" must modify the subject of the main clause, the person who trained. In the original (Choice A), the subject of the main clause is "the marathon route," which cannot do any training; this is a dangling modifier. Choice B correctly places "the young runner" as the subject, so the participial phrase logically modifies her. Choice C repeats the same dangling modifier error with a passive construction. Choice D fixes the dangling modifier but introduces the vague pronoun "her," which has no clear antecedent in the sentence.

Question 2. Which choice makes the sentence most grammatically acceptable?

• A) No Change (it has survived two earthquakes and three major floods)
• B) it has survived two earthquakes, and three major floods
• C) however, it has survived two earthquakes and three major floods
• D) and has survived two earthquakes and three major floods ✓

Explanation: Choice D is correct. The original sentence is a fused (run-on) sentence: two independent clauses joined with no punctuation or conjunction. Choice D replaces the second subject "it" with the coordinating conjunction "and," making the second clause share the subject "The bridge" and turning the whole sentence into one grammatically complete unit. Choice A is a fused sentence. Choice B adds a comma inside the second clause but still leaves the two independent clauses fused. Choice C inserts "however", a conjunctive adverb, but without a semicolon before it, the sentence remains a run-on; "however" alone cannot join two independent clauses.

Question 3. Which choice makes the sentence most grammatically acceptable?

• A) No Change (how they sustain thousands of species, and how warming oceans threaten their survival.) ✓
• B) how they sustain thousands of species, and warming oceans threaten their survival.
• C) sustaining thousands of species, and how warming oceans threaten their survival.
• D) they sustain thousands of species, and how warming oceans threaten their survival.

Explanation: Choice A (No Change) is correct. The sentence lists three parallel noun clauses as objects of "explores": "how coral reefs form," "how they sustain thousands of species," and "how warming oceans threaten their survival." All three begin with "how" followed by a subject and verb, perfectly parallel. Choice B breaks the pattern by dropping "how" from the third element, making the last clause a standalone independent clause rather than a noun clause. Choice C replaces the second "how" clause with a participial phrase ("sustaining..."), destroying the parallel structure. Choice D drops "how" from the second element, again breaking the parallel series of "how" clauses.

Question 4. Which choice makes the sentence most grammatically acceptable?

• A) No Change (discovered a new exoplanet orbiting a distant star with a powerful telescope.)
• B) discovered, with a powerful telescope, a new exoplanet orbiting a distant star
• C) used a powerful telescope to discover a new exoplanet, which orbited a distant star, ✓
• D) discovered a new exoplanet, with a powerful telescope, orbiting a distant star

Explanation: Choice C is correct. In the original (Choice A), the phrase "with a powerful telescope" is placed immediately after "distant star," making it sound as if the star possesses a powerful telescope, a clear misplaced modifier. Choice C rewrites the sentence to unambiguously attach the telescope to the act of discovering. Choice B places "with a powerful telescope" between commas after the verb, which is grammatically acceptable and clear; however, Choice C is more precise because it restructures the sentence to eliminate any possible ambiguity. Choice D places the telescope phrase between "exoplanet" and "orbiting," which still creates ambiguity about what the telescope modifies.

Question 5. Which choice makes the sentence most grammatically acceptable?

• A) No Change (which was donated to the city in 1923 by a local merchant who had made his fortune in the timber industry.)
• B) was donated to the city in 1923 by a local merchant who had made his fortune in the timber industry. ✓
• C) which had been donated to the city in 1923, by a local merchant who made his fortune in the timber industry.
• D) donated to the city in 1923 by a local merchant, who had made his fortune in the timber industry.

Explanation: Choice B is correct. The original (Choice A) is a sentence fragment: "The old library on Elm Street" is the subject, but everything that follows is a relative clause beginning with "which"; there is no main verb for the subject. Choice B removes "which was" and replaces it with the simple past verb "was donated," giving the subject its main verb and completing the sentence. Choice C retains "which," leaving the fragment intact regardless of other adjustments. Choice D replaces "which was donated" with a participial phrase "donated," which still leaves the subject without a main verb, producing another fragment.