SAT Boundaries (Medium) - English – Real Collegeboard Practice Questions with Answers and Explanations

Choice D is the best answer. The convention being tested is the punctuation of a supplementary element within a sentence. The comma after “(13C)” pairs with the comma after “isotope” to separate the supplementary element “carbon-13 (13C)” from the rest of the sentence. This supplementary element defines the “rare carbon isotope,” and the pair of commas indicates that this element could be removed without affecting the grammatical coherence of the sentence. Choice A is incorrect because it fails to use appropriate punctuation to separate the supplementary element “carbon-13 (13C)” from the rest of the sentence. Choice B is incorrect because it fails to use appropriate punctuation to separate the supplementary element “carbon-13 (13C)” from the rest of the sentence. Choice C is incorrect because it fails to use appropriate punctuation to separate the supplementary element “carbon-13 (13C)” from the rest of the sentence. The comma after “carbon-13” isn’t necessary because the parentheses around “13C” already separate this element from the rest of the sentence.

Choice C is the best answer. The convention being tested is the punctuation of a supplementary element within a sentence. The comma after “nutrients” pairs with the comma after “photosynthesis” to separate the supplementary element “the mechanism by which plants use sunlight to turn carbon dioxide and water into nutrients” from the rest of the sentence. This supplementary element functions to define the term “photosynthesis,” and the pair of commas indicates that this element could be removed without affecting the grammatical coherence of the sentence. Choice A is incorrect because it fails to use appropriate punctuation to separate the supplementary element from the rest of the sentence. Choice B is incorrect because a conjunction can’t be paired with a comma in this way to separate the supplementary element from the rest of the sentence. Choice D is incorrect because a dash can’t be paired with a comma in this way to separate the supplementary element from the rest of the sentence.

Choice D is the best answer. The convention being tested is punctuation use between sentences. In this choice, the period is used correctly to mark the boundary between one sentence (“Defying…fast”) and another sentence that begins with a supplementary phrase (“During…Olympics”). Choice A is incorrect. When a dash is present in a sentence (“ran—fast”), it’s not conventional to use another dash (“fast— during”) to mark the boundary between sentences because it creates a potentially confusing sentence. In this context, a period, semicolon, or colon would be clear and more conventional. Choice B is incorrect because it results in a run-on sentence. The sentences (“Defying…fast”) and (“during…Olympics”) are fused without punctuation and/or a conjunction. Choice C is incorrect because it results in a comma splice. A comma can’t be used in this way to mark the boundary between sentences.

Choice D is the best answer. The convention being tested is the coordination of main clauses within a sentence. This choice correctly uses a comma and the coordinating conjunction “and” to join the first main clause (“He…1680”) and the second main clause (“as…time”). Choice A is incorrect because it results in a run-on sentence. The two main clauses are fused without punctuation and/or a conjunction. Choice B is incorrect because when coordinating two longer main clauses such as these, it’s conventional to use a comma before the coordinating conjunction. Choice C is incorrect because it results in a comma splice. Without a conjunction following it, a comma can’t be used in this way to join two main clauses.

Choice D is the best answer. No punctuation should separate the subject of the sentence (“the Huntington Library in California”) from its verb (“received”). Choice A is incorrect. No punctuation should separate the subject of the sentence (“the Huntington Library in California”) from its verb (“received”). Choice B is incorrect. No punctuation should separate the subject of the sentence (“the Huntington Library in California”) from its verb (“received”). Choice C is incorrect. No punctuation should separate the subject of the sentence (“the Huntington Library in California”) from its verb (“received”).

Choice C is the best answer. The phrase “making…at the time” provides additional information about Cahokia that’s not required for the sentence to make sense or function grammatically. As a nonessential supplement, this phrase should be separated from the rest of the sentence with a comma. Choice A is incorrect. This choice results in a run-on sentence. The nonessential descriptive aside “making…at the time” needs to be separated from the rest of the sentence with a comma. Choice B is incorrect. This choice results in a sentence fragment. “Making…at the time” doesn’t have a subject and can’t stand on its own as a sentence. Thus, it can’t be separated from the rest of the sentence with a period. Choice D is incorrect. This choice results in a punctuation error. “Making…at the time” doesn’t have a subject and can’t stand on its own as an independent clause. Since a semicolon can only link two independent clauses, using one here creates an error.

Choice B is the best answer. Both clauses in this sentence could stand alone as complete sentences, which means they are both independent clauses. This choice uses a comma plus a coordinating conjunction to link them together, which is one of the correct ways to link two independent clauses. Choice A is incorrect. This choice results in a run-on sentence error. Both clauses in this sentence could stand alone as complete sentences, which means they are both independent clauses. A comma by itself is not enough punctuation to link two independent clauses. Choice C is incorrect. This choice results in a run-on sentence error. Both clauses in this sentence could stand alone as complete sentences, which means they are both independent clauses. Independent clauses can only be linked in a few ways, including with a comma plus a coordinating conjunction. This choice uses the coordinating conjunction “and,” but it is missing the comma beforehand. Choice D is incorrect. This choice results in a run-on sentence error. Both clauses in this sentence could stand alone as complete sentences, which means they are both independent clauses. Independent clauses need to have certain kinds of punctuation marks between them. This choice doesn’t use any punctuation between the two clauses.

Choice B is the best answer. The phrase “according to Swentzell” is an aside that interrupts the flow of the sentence, so it needs to be separated from the sentence with a pair of matching punctuation marks: two commas, two dashes, or a pair of parentheses. We already have a comma before “according,” so we must add a comma after “Swentzell.” . Choice A is incorrect. This choice creates a punctuation error. The phrase “according to Swentzell” is an aside that interrupts the flow of the sentence, so it needs to be separated from the sentence with a pair of matching punctuation marks: one before and one after the phrase. Choice C is incorrect. This choice creates a punctuation error. “The arrangement of the figures, according to Swentzell” is not an independent clause, so it can’t come before a colon. Choice D is incorrect. This choice creates a punctuation error. The phrase “according to Swentzell” is an aside that interrupts the flow of the sentence, so it needs to be separated from the sentence with a pair of matching punctuation marks. We already have a comma at the beginning, so we have to use another comma here to match. We can’t just switch to a dash! .

Choice A is the best answer. “Nine months…offense” and “according to…system” are both independent clauses. Separating them with a period and turning them into their own sentences is the only grammatically correct choice among the provided options. Choice B is incorrect. This choice results in a comma splice error, which is a punctuation error that occurs when two independent clauses are joined by only a comma. “Nine months…offense” and “according to…system” are both independent clauses, so they need to be either joined by a semicolon, joined by a comma and a coordinating conjunction, or separated by a period. Choice C is incorrect. This choice results in a run-on sentence, which occurs when two independent clauses are joined without punctuation. “Nine months…offense” and “according to…system” are both independent clauses, so they need to be either joined by a semicolon, joined by a comma and a coordinating conjunction, or separated by a period. Choice D is incorrect. This choice results in a run-on sentence, which occurs when two independent clauses are joined without punctuation. “Nine months…offense” and “according to…system” are independent clauses, so we would need to put a comma before the coordinating conjunction “and” to join them properly.

Choice D is the best answer. The convention being tested is punctuation use between sentences. In this choice, the period is used correctly to mark the boundary between one sentence (“In 2017...Nutcracker”) and another (“According...culture”). The supplementary element “according to reviewers” modifies the main clause of the second sentence (“the Toledos’...culture”). Choice A is incorrect because it results in a run-on sentence. The sentences are fused without punctuation and/or a conjunction. Furthermore, no punctuation is needed within the supplementary element “according to reviewers.” Choice B is incorrect because it results in a comma splice. A comma can’t be used in this way to mark the boundary between sentences. Choice C is incorrect because it results in a run-on sentence. The sentences are fused without punctuation and/or a conjunction.

Choice C is the best answer. The convention being tested is the coordination of main clauses within a sentence. This choice uses a semicolon in a conventional way to join the first main clause (“It is…ones”) and the second main clause (“even so… needs”). Furthermore, the placement of the semicolon after “ones” indicates that the supplementary phrase “even so” modifies the following clause (“the reawakening...needs”), resulting in the most logical and grammatically complete sentence. With this punctuation, the sentence logically indicates that the recent interest in an old technology like steam engines is despite the fact that technological change typically seeks out new technologies. Choice A is incorrect because it results in a confusing and illogical sentence. Placing the semicolon after “so” indicates that the supplementary element “even so” modifies the first clause of the sentence, which doesn’t make sense in this context. Choice B is incorrect because it results in a run-on sentence. It fails to mark the boundary between the two main clauses with appropriate punctuation. Choice D is incorrect because it results in a comma splice. Without a conjunction following it, a comma can’t be used in this way to join the two main clauses of the sentence.

Choice A is the best answer. The convention being tested is punctuation use between sentences. In this choice, the period is used correctly to mark the boundary between one sentence (“However...earlier”) and another (“In...area”). The supplementary phrase “in 1420 CE” modifies “humans,” the subject of the third sentence. Choice B is incorrect because it results in a comma splice. A comma can’t be used in this way to mark the boundary between sentences. Choice C is incorrect because it results in a comma splice. A comma can’t be used in this way to mark the boundary between sentences. Moreover, the subordinating conjunction “which” creates a confusing and illogical sentence that suggests that the supplementary phrase beginning with “in” modifies the previous information (“However...earlier”) rather than the information that follows. Choice D is incorrect because it results in a run-on sentence. The sentences (“However...earlier” and “in...area”) are fused without punctuation and/or a conjunction.

Choice D is the best answer. The convention being tested is the coordination of main clauses. This choice correctly uses a comma and the coordinating conjunction “but” to join the first main clause (“Materials…Ru”) and the second main clause (“the alloy…NiCoCr”). Choice A is incorrect because it results in a run-on sentence. The two main clauses are fused without punctuation and/or a conjunction. Choice B is incorrect because when coordinating two longer main clauses such as these, it’s conventional to use a comma before the coordinating conjunction. Choice C is incorrect because it results in a comma splice. Without a conjunction following it, a comma can’t be used in this way to join two main clauses.

Choice D is the best answer. The word “falling” occurs in the middle of a clause and isn’t part of a supplement, so we don’t need any punctuation after it. We can see this more clearly if we simplify the rest of the sentence: “The reason seeds appear to float while falling is that their plumes enhance drag.” . Choice A is incorrect. This doesn’t complete the text in a way that conforms to the conventions of Standard English. The word “falling” occurs in the middle of a clause and isn’t part of a supplement, so we don’t need any punctuation after it. We can see this more clearly if we simplify the sentence: “The reason seeds appear to float while falling is that their plumes enhance drag.” . Choice B is incorrect. This doesn’t complete the text in a way that conforms to the conventions of Standard English. The word “falling” occurs in the middle of a clause and isn’t part of a supplement, so we don’t need any punctuation after it. We can see this more clearly if we simplify the sentence: “The reason seeds appear to float while falling is that their plumes enhance drag.” . Choice C is incorrect. This doesn’t complete the text in a way that conforms to the conventions of Standard English. The word “falling” occurs in the middle of a clause and isn’t part of a supplement, so we don’t need any punctuation after it. We can see this more clearly if we simplify the sentence: “The reason seeds appear to float while falling is that their plumes enhance drag.” .

Choice B is the best answer. There are two independent clauses in the sentence, each with a subject and a verb: "many...were skeptical" and "historians have determined…." These clauses can be grammatically joined by a comma and the coordinating conjunction "but." Choice A is incorrect. This choice results in a run-on sentence, which occurs when two independent clauses are joined without punctuation. Two independent clauses can’t be joined by just the coordinating conjunction "but." A comma would also be required. Choice C is incorrect. This choice creates a punctuation error called a comma splice. This sentence contains two independent clauses ("Many…were skeptical" and "historians have determined…"). A comma alone can’t join two independent clauses. That requires a comma and a coordinating conjunction. Choice D is incorrect. This choice results in a run-on sentence, which occurs when two independent clauses are joined without punctuation. This sentence contains two independent clauses ("Many…were skeptical" and "historians have determined…"), which need to be either joined by a semicolon, joined by a comma and a coordinating conjunction, or separated by a period.

Choice D is the best answer. “A combination of fiction and memoir, poetry and prose” is a nonessential supplement, so it needs to be set off from the rest of the sentence with a pair of matching punctuation marks. We already have a dash at the beginning of the supplement, so we need to add a dash at the end of the supplement to match. Choice A is incorrect. This doesn’t complete the text in a way that conforms to the conventions of Standard English. “A combination of fiction and memoir, poetry and prose” is a nonessential supplement, so it needs to be set off from the rest of the sentence with a pair of matching punctuation marks. We already have a dash at the beginning of the supplement, so we need to add a dash at the end of the supplement to match. Choice B is incorrect. This doesn’t complete the text in a way that conforms to the conventions of Standard English. “A combination of fiction and memoir, poetry and prose” is a nonessential supplement, so it needs to be set off from the rest of the sentence with a pair of matching punctuation marks. We already have a dash at the beginning of the supplement, so we need to add a dash at the end of the supplement to match. Choice C is incorrect. This doesn’t complete the text in a way that conforms to the conventions of Standard English. “A combination of fiction and memoir, poetry and prose” is a nonessential supplement, so it needs to be set off from the rest of the sentence with a pair of matching punctuation marks. We already have a dash at the beginning of the supplement, so we need to add a dash at the end of the supplement to match.

Choice C is the best answer. The convention being tested is the punctuation of a supplementary element within a sentence. The comma after “method” pairs with the comma after the closing parenthesis to separate the supplementary element “called ELISA (enzyme-linked immunosorbent assay)” from the rest of the sentence. This supplementary element functions to identify the name of Engvall and Perlmann’s method, and the pair of commas indicates that this element could be removed without affecting the grammatical coherence of the sentence. Choice A is incorrect because an opening parenthesis can’t be paired with a comma to separate the supplementary element from the rest of the sentence. Choice B is incorrect because a dash can’t be paired with a comma to separate the supplementary element from the rest of the sentence. Choice D is incorrect because it fails to use appropriate punctuation to separate the supplementary element from the rest of the sentence.

Choice A is the best answer. “A team…tried something new” is an independent clause leading to an explanation of what the new thing was. A colon can only be used at the end of an independent clause, and typically introduces further explanation that expands upon the first clause, which makes a colon the perfect choice here. Choice B is incorrect. This choice results in a punctuation error. “Sequencing…dental plaque” can’t stand on its own as a sentence, and so it can’t be linked to the independent clause “a team…tried something new” with a semicolon. Only two independent clauses can be connected in this way. Choice C is incorrect. This choice results in a punctuation error. If “sequencing” is included in the first clause, it can no longer stand on its own as a complete idea. Since a colon can only come at the end of an independent clause, using one in this way creates an error. Choice D is incorrect. This choice results in a sentence fragment. “Sequencing…dental plaque” can’t stand on its own as a sentence.

Choice C is the best answer. The convention being tested is punctuation between a supplementary phrase and a main clause. This choice correctly uses a comma to mark the boundary between the supplementary phrase (“powered…day”), which describes how the LEDs are powered, and the main clause (“the blinking…night”). Choice A is incorrect because it fails to mark the boundary between the supplementary phrase and the main clause with appropriate punctuation. Furthermore, placing commas around the phrase “by solar panels” suggests that it could be removed without affecting the coherence of the sentence, which isn’t the case. Choice B is incorrect because it fails to mark the boundary between the supplementary phrase and the main clause with appropriate punctuation. Choice D is incorrect. Placing commas around the phrase “collected by solar panels during the day″ suggests that it could be removed without affecting the coherence of the sentence, which isn’t the case.

Choice D is the best answer. This choice correctly uses a semicolon to punctuate a complex list (which is made up of items that have commas in them). Choice A is incorrect. This is a complex list, indicated by the semicolon between "1998" and "Carolyn Bertozzi." What comes after the blank is a separate list item, so punctuation is needed after "Stanford." Choice B is incorrect. This is a complex list, indicated by the semicolon between "1998" and "Carolyn Bertozzi." The items in this list have internal punctuation in the form of commas and must therefore be separated by semicolons to avoid confusion. Choice C is incorrect. This is a complex list, indicated by the semicolon between "1998" and "Carolyn Bertozzi." Colons aren’t used to separate items in a list.

Choice A is the best answer. The convention being tested is punctuation use between a main clause and a participial phrase. This choice correctly uses a comma to mark the boundary between the main clause (“Epicurus…‘soul’”) and the participial phrase (“positing…absence”) that provides additional information about how Epicurus defined pleasure. Choice B is incorrect because a colon can’t be used in this way to join a main clause and a participial phrase. Choice C is incorrect because a semicolon can’t be used in this way to join a main clause and a participial phrase. Choice D is incorrect because it results in a rhetorically unacceptable sentence fragment beginning with “positing.”