English Grammar & Syntax Quiz: Punctuating Relative Clauses
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Punctuating Relative ClausesQuestion 1 of 10

The label MS-17 uniquely identifies a manuscript in the museum's collection. Its discovery location is already described elsewhere in the exhibit.

Which sentence correctly punctuates the relative clause containing supplementary information?

The manuscript labeled MS-17 which was found behind a false panel will be displayed in June.
The manuscript labeled MS-17, which was found behind a false panel will be displayed in June.
The manuscript labeled MS-17, which was found behind a false panel, will be displayed in June.
The manuscript labeled MS-17 which was found behind a false panel, will be displayed in June.
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English Grammar & Syntax Quiz

English Grammar & Syntax Quiz: Punctuating Relative Clauses

Practice Punctuating Relative Clauses in English Grammar & Syntax with focused quiz questions that help you check what you know, review explanations, and build confidence with test-style prompts.

What this quiz covers

This quiz focuses on Punctuating Relative Clauses, giving you a quick way to practice the rules, question types, and explanations that matter most for English Grammar & Syntax.

How to use this quiz

Try each quiz question before looking at the correct answer. Use the explanations to review missed ideas, then come back to similar questions until the pattern feels familiar.

All questions

Question 1

The label MS-17 uniquely identifies a manuscript in the museum's collection. Its discovery location is already described elsewhere in the exhibit.

Which sentence correctly punctuates the relative clause containing supplementary information?

  1. The manuscript labeled MS-17 which was found behind a false panel will be displayed in June.
  2. The manuscript labeled MS-17, which was found behind a false panel will be displayed in June.
  3. The manuscript labeled MS-17, which was found behind a false panel, will be displayed in June. (correct answer)
  4. The manuscript labeled MS-17 which was found behind a false panel, will be displayed in June.
Explanation: When a relative clause adds supplementary (non-essential) information about a noun that's already uniquely identified, it must be set off with commas on both sides. Think of these commas like parentheses — they signal that you could lift the clause out entirely and the sentence would still make complete sense and refer to the same specific thing. Here, "MS-17" already pinpoints exactly which manuscript is meant, so the clause "which was found behind a false panel" is purely bonus detail, not a defining characteristic. That makes it a non-restrictive relative clause, which always requires commas before and after it. Choice C correctly wraps the clause with a comma before "which" and a comma after "panel," giving you a clean, grammatically complete sentence when the clause is removed: The manuscript labeled MS-17 will be displayed in June. That's your confirmation it's working properly. Choice A has no commas at all, making the clause look restrictive — as if the discovery location is what distinguishes this manuscript from others. It isn't; MS-17 already does that job. Choice B places a comma before "which" but omits the closing comma after "panel," leaving the clause improperly attached to the main verb "will be displayed." This creates a structural break where there shouldn't be one. Choice D does the opposite — it omits the opening comma but inserts one after "panel," which incorrectly separates the subject from its verb. A reliable rule to remember: non-restrictive relative clauses need two commas, one on each side, every time. If you only see one, the punctuation is broken.

Question 2

The city operates two observatories. The riverside observatory is closed for renovations, but the one on the hill is still operating.

Which sentence uses commas correctly to identify the observatory that remains open?

  1. The observatory, that stands on the hill, remains open to researchers.
  2. The observatory that stands on the hill remains open to researchers. (correct answer)
  3. The observatory, that stands on the hill remains open to researchers.
  4. The observatory that stands on the hill, remains open to researchers.
Explanation: When a sentence contains a clause that identifies which one out of multiple possibilities, that clause is restrictive — it's essential to the meaning and should never be set off with commas. This question tests exactly that distinction, and the context clue is built right into the passage: there are two observatories, so you need the clause "that stands on the hill" to specify which observatory remains open. Remove it, and the sentence becomes ambiguous. That's why B is correct. "The observatory that stands on the hill remains open to researchers" contains a restrictive relative clause with no commas — exactly right, because the clause is doing necessary identifying work. A wraps the clause in commas, which signals a non-restrictive (parenthetical) clause — one that adds bonus information about an already-identified subject. But here, the clause isn't bonus information; it's the only thing distinguishing this observatory from the other one. Using commas in A implies there's only one observatory, which contradicts the passage. C places a comma only before the clause but not after, creating a grammatically lopsided structure. Non-restrictive clauses require commas on both sides if they appear mid-sentence, so C is inconsistent and incorrect. D puts a comma after the clause ("the hill,"), which wrongly separates the subject from its verb and disrupts the sentence's grammatical flow entirely. A quick tip: ask yourself, "Does this clause tell me which one?" If yes, it's restrictive — no commas. If it just adds extra detail about something already identified, use commas on both sides.

Question 3

Six sensors were tested. The phrase "that failed overnight" identifies one of them; after that sensor has been identified, its recent installation is supplementary information.

Which sentence correctly punctuates the two adjacent relative clauses?

  1. The sensor, that failed overnight, which had been installed last week, was returned to the manufacturer.
  2. The sensor that failed overnight which had been installed last week was returned to the manufacturer.
  3. The sensor that failed overnight, which had been installed last week, was returned to the manufacturer. (correct answer)
  4. The sensor, that failed overnight which had been installed last week, was returned to the manufacturer.
Explanation: When a sentence contains two relative clauses back-to-back, you need to ask one question about each: does it identify the noun, or does it add extra detail about an already-identified noun? Restrictive clauses identify and require no commas; non-restrictive clauses add supplementary information and must be set off with commas. In this sentence, "that failed overnight" is doing essential work — it picks out one specific sensor from among six. Without it, you wouldn't know which sensor is being discussed, so it's restrictive and takes no commas. Once that sensor is identified, "which had been installed last week" layers on a bonus detail about it. That detail is non-restrictive and must be enclosed with a comma before and after — except here, since the clause ends mid-sentence before the verb, a single preceding comma plus the natural sentence boundary handles it. That reasoning leads you directly to C. A is wrong because it places commas around "that failed overnight," treating a restrictive clause as non-restrictive and incorrectly using that in a non-restrictive role — that never introduces non-restrictive clauses. B removes all commas, which correctly handles the restrictive clause but leaves the non-restrictive "which" clause without its required comma, fusing the two clauses awkwardly. D groups both clauses inside one set of commas, which misrepresents their relationship and again pairs that with commas — a reliable error signal. A handy rule of thumb: that = restrictive (no commas), which = non-restrictive (commas required). When you spot both in the same sentence, treat them independently and punctuate each on its own terms.

Question 4

The board has already selected one report for publication. The auditors' revisions are supplementary information, and the publication is scheduled for Friday.

Which sentence correctly sets off the relative clause without separating the final time phrase from the main clause?

  1. The board will publish the report which the auditors revised twice, on Friday.
  2. The board will publish the report, which the auditors revised twice on Friday.
  3. The board will publish the report which the auditors revised twice on Friday.
  4. The board will publish the report, which the auditors revised twice, on Friday. (correct answer)
Explanation: When a sentence contains a relative clause (a "which" clause) alongside an adverbial phrase (like a time expression), your job is to keep each modifier clearly attached to the right element — and commas are your primary tool for doing that. In this sentence, "which the auditors revised twice" is a non-restrictive relative clause — it adds extra information about a report that's already been specifically identified (the board selected one report, so we already know which one). Non-restrictive clauses must be set off with commas on both sides. The phrase "on Friday" modifies the main verb "will publish," telling us when the publishing happens — so it must stay attached to the main clause, not get buried inside the relative clause. Answer D — "The board will publish the report, which the auditors revised twice, on Friday" — does exactly this. Commas bracket the relative clause, and "on Friday" clearly modifies the publishing event. This is the correct answer. Answer A places "on Friday" after the closing comma, which looks acceptable at first, but without a comma before "which," the clause reads as restrictive, implying there are multiple reports and this specifies the one revised on Friday — contradicting the passage. Answer B omits the closing comma after the relative clause, fusing "on Friday" into the clause itself, making it seem the auditors revised the report on Friday rather than that the publication is on Friday. Answer C has no commas at all around the relative clause, making it restrictive and again misplacing the time phrase inside it. Strategy tip: Whenever you see a "which" clause alongside a time or place phrase, ask yourself two questions: Is this clause non-restrictive (needing two commas)? And does the modifier belong to the clause or the main verb? Keeping those roles separate will guide your comma placement every time.

Question 5

The network policy divides devices into two groups: those supporting AES-256 encryption and those lacking that capability. Only the first group may connect.

Which sentence correctly punctuates the relative clause, regardless of the use of the relative pronoun "which"?

  1. Devices, which support AES-256 encryption, may connect to the secure network.
  2. Devices which support AES-256 encryption may connect to the secure network. (correct answer)
  3. Devices, which support AES-256 encryption may connect to the secure network.
  4. Devices which support AES-256 encryption, may connect to the secure network.
Explanation: When a relative clause restricts the meaning of a noun — that is, it identifies which specific subset you mean rather than adding bonus information about all members — it must not be set off by commas. This is the defining vs. non-defining (restrictive vs. non-restrictive) relative clause distinction, and it's exactly what this question tests. The passage makes clear that only some devices may connect: those with AES-256 encryption. That means the clause "which support AES-256 encryption" is doing essential identifying work — it tells you which devices qualify. Restrictive clauses require no commas, making B the correctly punctuated sentence. Here's why each other option fails. A wraps the clause in commas, turning it non-restrictive. That punctuation signals the clause is merely extra information about all devices — implying every device may connect, which contradicts the passage's meaning. C places a comma only after the clause's opening, creating an asymmetrical, grammatically broken structure; non-restrictive clauses need commas on both sides (or just at the end if the clause closes the sentence). D places a comma after the clause and before the main verb "may connect," which illogically separates the subject from its predicate with no grammatical justification. A reliable strategy: ask yourself, "Could I remove this clause without changing who or what I'm talking about?" If removing it would lose critical identifying information (as here — removing the clause would imply all devices connect), the clause is restrictive and should appear without commas. Bookmark this test; it catches many students off guard.

Question 6

A historical survey identifies one bridge as the oldest in the town. The age of that bridge's stone piers is additional information rather than a means of identifying the bridge.

Which sentence correctly punctuates the relative clause?

  1. The town's oldest bridge, whose stone piers date to 1812, will close for repairs. (correct answer)
  2. The town's oldest bridge whose stone piers date to 1812 will close for repairs.
  3. The town's oldest bridge, whose stone piers date to 1812 will close for repairs.
  4. The town's oldest bridge whose stone piers date to 1812, will close for repairs.
Explanation: When you see a relative clause question, your first task is to determine whether the clause is restrictive or non-restrictive. A restrictive clause identifies which thing you mean — it's essential, so no commas. A non-restrictive clause adds bonus information about something already clearly identified — it's set off with commas. Here, the passage tells you the bridge has already been uniquely identified: it's the town's oldest bridge. There's only one. The clause "whose stone piers date to 1812" doesn't help you pick which bridge — it just adds an interesting detail. That makes it non-restrictive, requiring commas on both sides of the clause. Choice A does exactly this: a comma before whose and a comma after 1812, cleanly wrapping the clause. This is the correct answer. Choice B omits both commas entirely, treating the clause as restrictive — as though you needed the pier information to identify which bridge you mean. You don't; the superlative "oldest" already does that job. Choice C places a comma before the clause but forgets the closing comma after 1812, leaving the sentence structurally lopsided — the clause bleeds into the main verb without a clean boundary. Choice D does the opposite: no opening comma before whose, but a stray comma after 1812, which awkwardly separates the subject from its verb. A useful rule of thumb: if you can delete the clause and the sentence still points to the same specific thing, you need commas around it. Test every relative clause this way before choosing your answer.

Question 7

The institution has only one east archive, and its reopening date is background information. Within that archive, only documents needing climate control are stored in the new vault.

Which sentence correctly punctuates both relative clauses?

  1. The east archive which reopened in May stores documents, that require climate control.
  2. The east archive, which reopened in May, stores documents, that require climate control.
  3. The east archive, which reopened in May, stores documents that require climate control. (correct answer)
  4. The east archive which reopened in May stores documents that require climate control.
Explanation: When you see relative clauses in a sentence, your first job is to ask: is this information essential or extra? A restrictive clause limits which specific thing you mean — it's essential, so no commas. A non-restrictive clause adds bonus information about something already uniquely identified — it gets set off with commas. The passage tells you two things: there is only one east archive, and only some documents (those needing climate control) are stored in the vault. That distinction drives every punctuation decision here. Because the institution has only one east archive, saying "which reopened in May" doesn't help identify which archive — it just adds a detail about the one that already exists. That makes it non-restrictive, requiring commas around it. On the other hand, "that require climate control" tells you which documents are stored there — not all documents, only those specific ones. That clause is restrictive, so no commas belong around it. Choice C gets both right: commas around "which reopened in May," and no comma before "that require climate control." Choice A drops the commas around the archive clause, treating unique background information as though it were identifying — and wrongly adds a comma before the restrictive "that" clause. Choice B correctly punctuates the archive clause but then incorrectly sets off "that require climate control" with a comma, implying all documents are stored there, which contradicts the passage. Choice D omits the necessary commas around the non-restrictive archive clause, making it look like there might be multiple archives. A handy rule of thumb: which often signals non-restrictive (use commas); that almost always signals restrictive (no commas). When in doubt, check whether the clause identifies or merely describes.

Question 8

Twenty interns applied for travel funding, but only the interns who submitted their forms by noon are eligible.

Which sentence correctly punctuates the clause that determines eligibility?

  1. The interns, who submitted their forms by noon, are eligible for travel funding.
  2. The interns, who submitted their forms by noon are eligible for travel funding.
  3. The interns who submitted their forms by noon, are eligible for travel funding.
  4. The interns who submitted their forms by noon are eligible for travel funding. (correct answer)
Explanation: When you see a relative clause modifying a noun, ask yourself one question: does this clause identify which specific members of the group we mean, or does it just add bonus information about an already-identified group? That distinction — between restrictive and non-restrictive clauses — is exactly what this question tests. Here, the passage establishes that only some interns (those who submitted forms by noon) are eligible. The clause "who submitted their forms by noon" isn't decorative — it's doing essential work to specify which interns qualify. That makes it a restrictive clause, and restrictive clauses never take commas. Answer D is correct because it presents the clause with no commas, keeping the identifying information tightly bound to "interns." Answer A wraps the clause in commas on both sides, treating it as non-restrictive. This implies all interns submitted on time and are eligible — which directly contradicts the passage's setup of a selective group. B makes the same non-restrictive error with an opening comma but then forgets the closing comma, creating a dangling, malformed structure. C places a comma only after the clause, which awkwardly separates the subject ("interns who submitted their forms by noon") from its predicate ("are eligible") — no comma should ever interrupt that connection. A reliable test: try removing the clause. If the sentence loses its essential meaning or becomes false ("The interns are eligible" — but which interns?), the clause is restrictive and needs no commas. Memorize this: essential = no commas, extra = comma pair.

Question 9

Mara owned only one bicycle for making deliveries. She sold it after a mechanic discovered damage to its frame.

Which sentence correctly reflects the information in the passage?

  1. Mara sold her delivery bicycle, which had developed a crack in its frame. (correct answer)
  2. Mara sold her delivery bicycle which had developed a crack in its frame.
  3. Mara sold her delivery bicycle which, had developed a crack in its frame.
  4. Mara sold her delivery bicycle, which had developed, a crack in its frame.
Explanation: When a sentence contains a relative clause (a clause beginning with which, who, or that), you need to ask yourself: is this clause essential or nonessential to identifying the noun it modifies? If removing the clause would leave the reader confused about which thing you mean, it's essential — no commas. If the noun is already uniquely identified and the clause just adds extra information, it's nonessential — and you must surround it with commas. In the passage, Mara owned only one delivery bicycle. That means the clause "which had developed a crack in its frame" isn't identifying which bicycle — we already know. It's simply adding bonus information about that one bicycle. This makes it a nonessential (also called nonrestrictive) clause, which requires a comma before which. Choice A handles this perfectly: the comma before which signals the nonessential clause, and the sentence reads cleanly. Choice B drops the comma entirely, making the clause look restrictive — as if the sentence is distinguishing this bicycle from others Mara owned. That contradicts the passage. Choice C places the comma incorrectly after which, awkwardly splitting "which had developed" and creating a grammatical error — the clause no longer connects properly to the noun. Choice D inserts a comma after "developed," incorrectly separating the verb from its object ("a crack in its frame") with no grammatical justification. A handy tip: whenever you see which introducing a clause, ask whether the sentence still makes clear sense without it. If yes, you need a comma before which — and the answer is almost certainly the option with that comma placed correctly.

Question 10

Three researchers named Dr. Lee work at the institute. The one who directs the robotics laboratory is scheduled to speak before the others.

Which sentence correctly uses punctuation to distinguish the scheduled speaker?

  1. Dr. Lee, who directs the robotics laboratory, will speak first at the symposium.
  2. Dr. Lee who directs the robotics laboratory will speak first at the symposium. (correct answer)
  3. Dr. Lee, who directs the robotics laboratory will speak first at the symposium.
  4. Dr. Lee who directs the robotics laboratory, will speak first at the symposium.
Explanation: When a relative clause is the only thing distinguishing one person from several people with the same name, that clause is restrictive — it restricts which individual you mean — and restrictive clauses must appear without commas. This question tests whether you recognize that distinction. Because three researchers share the name Dr. Lee, the phrase "who directs the robotics laboratory" is essential information. Without it, your reader has no idea which Dr. Lee will speak first. That makes it a restrictive clause, and restrictive clauses are never set off by commas. Answer B correctly leaves the clause unpunctuated, keeping it fused to the noun it identifies: Dr. Lee who directs the robotics laboratory will speak first at the symposium. Answer A is the most tempting trap. The commas around "who directs the robotics laboratory" signal a nonrestrictive clause — one that merely adds extra, removable detail about a person already uniquely identified. That would only be appropriate if there were just one Dr. Lee. With three of them, those commas imply the clause is optional, which changes the meaning entirely. Answer C opens the clause with a comma but omits the closing comma, leaving the punctuation unbalanced and the sentence grammatically broken. Answer D has the same problem in reverse: no opening comma but a closing comma after the clause, creating an equally inconsistent and confusing structure. Your study tip: ask yourself, "Could I remove this clause and still know exactly who or which one is meant?" If yes → nonrestrictive → use commas. If no → restrictive → no commas.