SAT Sentence Boundaries Practice: Questions and Answers

Correct answer

Choice A: ;

Explanation

The instrument required frequent recalibration and the technicians checked it every morning are both independent clauses. A semicolon correctly joins them without a coordinating conjunction. A comma alone creates a comma splice, no punctuation creates a fused sentence, and placing a comma after and does not form a correct coordinated join. The full sentence is: The instrument required frequent recalibration; the technicians checked it every morning.

Why each choice is right or wrong

1. Choice A

   Correct answer

   A semicolon validly joins the two related independent clauses.

2. Choice B

   A comma alone cannot join these two independent clauses.

3. Choice C

   Without a joining word or boundary mark, the two clauses form a fused sentence.

4. Choice D

   The comma after and interrupts the second clause; the usual coordinated join would place a comma before and.

Correct answer

Choice D: :

Explanation

The words before the blank form an independent clause: Mira brought three tools to the repair session. The following list identifies those tools, so a colon is appropriate. A semicolon or period would leave a noun-list fragment afterward. And followed by a comma does not correctly connect or introduce this list.

Why each choice is right or wrong

1. Choice A

   A semicolon requires an independent clause after it; the tool list is not one.

2. Choice B

   A period would leave a clamp, a small wrench, and a brush as a sentence fragment.

3. Choice C

   And followed by a comma does not correctly connect or introduce the explanatory list.

4. Choice D

   Correct answer

   A colon can introduce this list after the complete independent clause.

Correct answer

Choice B: letters

Explanation

The full subject is The historian who cataloged the letters, and the main verb is published. The restrictive clause who cataloged the letters identifies which historian and is part of that subject. No punctuation belongs between the end of this subject and its verb. The completed sentence reads: The historian who cataloged the letters published a summary last year.

Why each choice is right or wrong

1. Choice A

   This comma incorrectly separates the subject, including its identifying clause, from published.

2. Choice B

   Correct answer

   No punctuation is needed between the complete subject and its main verb.

3. Choice C

   A semicolon would incorrectly split a subject from its predicate; the left side is not an independent clause.

4. Choice D

   A colon would also split the subject from its verb after an incomplete clause.