ACT English: Punctuation (Drill 3)

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

• A) No Change (railroad small towns)
• B) railroad, small towns ✓
• C) railroad; small towns
• D) railroad: small towns

Explanation: Choice B is correct. "In the decades following the completion of the transcontinental railroad" is an introductory prepositional phrase. A comma should follow an introductory phrase to separate it from the main clause ("small towns began sprouting up"). Choice A has no comma, running the introductory phrase directly into the main clause. Choice C uses a semicolon, which must separate two independent clauses — the introductory phrase is not a clause and cannot stand alone. Choice D uses a colon, which introduces a list or explanation after a complete independent clause; the introductory phrase here is neither.

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

• A) No Change (crumbling, Victorian-era, clocktower)
• B) crumbling Victorian-era, clocktower
• C) crumbling, Victorian-era clocktower ✓
• D) crumbling Victorian-era clocktower

Explanation: Choice C is correct. When two or more adjectives both modify a noun independently, they are separated by a comma. Here, "crumbling" and "Victorian-era" are coordinate adjectives that each independently describe "clocktower," so a comma between them is correct. However, "Victorian-era" is a compound adjective hyphenated to the noun it describes most directly — no comma goes between "Victorian-era" and "clocktower." Choice A places commas after both adjectives, incorrectly inserting one between "Victorian-era" and "clocktower." Choice B places no comma between the two coordinate adjectives "crumbling" and "Victorian-era," which is incorrect. Choice D omits all commas, treating neither pair as coordinate adjectives, which is also incorrect.

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

• A) No Change (that erosion has sculpted over millions of years) ✓
• B) that erosion has sculpted over millions of years,
• C) , that erosion has sculpted over millions of years, as punctuated in the sentence
• D) , that erosion has sculpted over millions of years

Explanation: Choice A (No Change) is correct. "That erosion has sculpted over millions of years" is a restrictive relative clause — it identifies which sandstone formations are meant. Restrictive clauses beginning with "that" are never set off by commas. Choice B adds a comma after the clause, incorrectly treating it as if it were a nonrestrictive clause — but it is essential to the meaning. Choices C and D use commas to set off the clause on one or both sides, which would be appropriate only for a nonrestrictive "which" clause. Swapping "that" for "which" and adding commas would also be acceptable, but adding commas while keeping "that" is always wrong.

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

• A) No Change (century it)
• B) century, it
• C) century, however, it
• D) century; it ✓

Explanation: Choice D is correct. The sentence contains two independent clauses: "Ocean thermal energy conversion has existed as a concept for over a century" and "it has only recently become economically viable." A semicolon is the correct punctuation to join two closely related independent clauses without a coordinating conjunction. Choice A has no punctuation between the clauses, creating a run-on sentence. Choice B uses a comma alone, which creates a comma splice — a comma cannot join two independent clauses without a coordinating conjunction. Choice C adds "however" with commas, making it a conjunctive adverb construction — this requires a semicolon before "however," not a comma, so this version is also a comma splice.

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

• A) No Change (years and its mirrors)
• B) years, and its mirrors ✓
• C) years; and its mirrors
• D) years, and, its mirrors

Explanation: Choice B is correct. The sentence joins two independent clauses with the coordinating conjunction "and": "The telescope had been in storage for thirty years" and "its mirrors were still in perfect condition." When a coordinating conjunction joins two independent clauses, a comma should precede it. "Years, and its mirrors" correctly places that comma. Choice A omits the comma, which is acceptable in very short sentences but is incorrect here where both clauses are substantial. Choice C places a semicolon before "and" — a semicolon already joins independent clauses on its own; adding "and" after it is redundant and nonstandard. Choice D adds a second comma after "and," incorrectly separating the conjunction from the clause it introduces.