Questions: Relative Clauses: Restrictive and Nonrestrictive

Question 1

Consider these two sentences: (A) 'The students who failed the exam received extra tutoring.' (B) 'The students, who failed the exam, received extra tutoring.' How do they differ in meaning?

• A. They mean the same thing; the commas in B are optional stylistic choices
• B. A refers only to the students who failed; B implies all students failed
• C. A is grammatically incorrect; relative clauses always require commas
• D. B is grammatically incorrect; 'who' should only be used for nonrestrictive clauses

Answer: (B)

This is the core insight of the restrictive/nonrestrictive distinction: the commas change meaning, not just style. In sentence A, the restrictive clause 'who failed the exam' identifies which students — only those who failed received tutoring. In sentence B, the nonrestrictive clause (set off by commas) implies the noun 'the students' is already identified as a complete group, and all of them failed. The same words produce opposite factual claims.

Question 2

In formal American English, which sentence is correctly punctuated?

• A. The report, that I submitted last week, was approved.
• B. The report which I submitted last week was approved.
• C. The report that I submitted last week was approved.
• D. The report, which I submitted last week was approved.

Answer: (C)

'That' introduces restrictive relative clauses and takes no commas; 'which' introduces nonrestrictive clauses and requires commas. Option C is correct: the clause 'that I submitted last week' restricts which report is meant, so 'that' is correct and no commas appear. Option A incorrectly uses commas with 'that.' Option B uses 'which' without commas, mixing the conventions. Option D correctly uses 'which' but omits the closing comma.

Question 3

In the sentence 'Maria, who studied most night, passed the exam,' removing the relative clause changes which person the sentence is about.

• T. True
• F. False

Answer: False

This is a nonrestrictive clause: Maria is already uniquely identified by name. The clause 'who studied all night' adds supplementary information but does not change who is being discussed. Remove it and you still have 'Maria passed the exam' — same person, same claim. The commas signal exactly this: the information is parenthetical, not identifying.

Question 4

In formal American English, 'that' can introduce both restrictive and nonrestrictive relative clauses.

• T. True
• F. False

Answer: False

'That' introduces only restrictive relative clauses. Nonrestrictive clauses use 'which' and are set off by commas. This is a convention of formal American English (British English is more flexible). Using 'that' with commas — 'The book, that I read, was excellent' — is a punctuation error, not just a stylistic difference.

Question 5

What two-part test can you apply to any relative clause to determine whether it is restrictive or nonrestrictive?

Model answer: Ask: (1) Is the noun already uniquely identified, or does this clause identify it? (2) Would removing the clause change which person or thing the noun refers to? If the clause is doing identifying work — if the noun would become ambiguous or refer to a different group without it — the clause is restrictive (no commas). If the noun is already pinned down and the clause adds a bonus fact, the clause is nonrestrictive (commas required).

This test is more reliable than memorizing rules about 'that' vs 'which' because it connects to the underlying logic: commas signal 'this information is extra,' and the absence of commas signals 'this information is essential to identify what I'm talking about.'