One deletion decides it
Every relative clause on this test belongs to exactly one of two families.
A restrictive clause narrows the noun it follows: it tells the reader which one. Delete it and the sentence either changes meaning or stops making sense. It takes no punctuation at all.
A non-restrictive clause adds information about a noun that is already fully identified. Delete it and the sentence still says the same thing. It must be enclosed by a matching pair — two commas, two dashes, or two parentheses.
The routine. Cover the clause with a finger. Read what is left. If the sentence is still complete and still points to the same thing, the clause is a supplement and needs a pair. If the sentence now names something vaguer or different, the clause is restrictive and takes nothing.
Học sinh Việt hay nhớ luật theo kiểu “which thì có phẩy, that thì không”. Luật đó đúng phần ngọn nhưng sai phần gốc: dấu phẩy không phụ thuộc vào từ nối, nó phụ thuộc vào việc mệnh đề đó có cần thiết để xác định danh từ hay không. Cứ xoá thử rồi đọc lại phần còn lại — đó là phép thử duy nhất, và nó không bao giờ sai.
The 1815 eruption of Mount Tamborawhich ejected some 150 cubic kilometres of rocklowered average global temperatures for two years.
- ,\ …\ ,
- ,\ …\ —
- —\ …\ ,
- (none)\ …\ (none)
Delete the middle clause: The 1815 eruption of Mount Tambora lowered average global temperatures for two years. Complete, and pointing at the same eruption — so the clause is a supplement and needs an enclosing pair. (B) and (C) mix a comma with a dash; (D) leaves a which clause naked, which the language does not allow. Answer (A).
Restrictive clauses take nothing — at either end
Restrictive. Volcanoes that erupt beneath thick ice sheets build flat-topped mountains called tuyas. Only some volcanoes do this; the clause says which ones. No commas.
Non-restrictive. Mount Rainier, which last erupted in the 1890s, is monitored continuously. The mountain is already identified by name; the clause is extra. Matching pair.
Volcanoeserupt beneath thick ice sheets build flat-topped mountains known as tuyas.
- that
- , which
- , that
- which,
Read (B) with the clause deleted: Volcanoes build flat-topped mountains known as tuyas — a claim about all volcanoes, which is false and is not what the sentence means. The clause is therefore restrictive: it picks out the subset. (C) is impossible in any sentence, because that never follows a comma; (D) puts the comma on the wrong side. Answer (A).
Two rules with no exceptions on this test. A clause introduced by that never takes a comma before it. A clause introduced by which or who that is being used non-restrictively must be closed as well as opened.
Researchers reanalysed the ice corethat had been stored in a university freezer since 1968.
- ,
- (no punctuation)
- ;
- —
That had been stored… identifies which core was reanalysed, so it is restrictive. A comma, a dash, or a semicolon would all cut the noun off from the clause that defines it, and a semicolon additionally demands an independent clause after it, which a relative clause is not. Answer (B).
Dấu phẩy đứng ngay trước that là sai trong mọi câu. Không cần đọc nghĩa, không cần xét ngữ cảnh — thấy “, that” trong một phương án thì loại ngay. Đây là phương án nhiễu được dùng lại nhiều nhất ở nhóm câu này vì đọc lướt nghe rất tự nhiên.
Choosing the relative word
When the four choices differ by one word rather than by punctuation, the question is which relative word the slot needs.
who — subject, refers to a person. whom — object, refers to a person.
whose — possessive, refers to a person or a thing: the next word is the thing
owned.
which — refers to a thing, non-restrictive on this test.
that — restrictive only.
where — refers to a physical place. when — refers to a time.
The astronomercatalogue of variable stars still underpins modern distance measurement spent her career classifying photographic plates.
- who
- whose
- which
- who's
The word after the blank is catalogue, a noun that belongs to the astronomer, so the slot needs the possessive relative. Who and which would each have to be the subject of the relative clause, but catalogue already fills that role; who's is the contraction of who is and cannot own anything. Answer (B).
Sedimentary basinsorganic material accumulates faster than it decays eventually yield petroleum.
- which
- where
- that
- in that
Strip the clause: organic material accumulates faster than it decays is already complete, with its own subject and verb. So the slot is not filled by a subject or an object pronoun — which and that would both need a grammatical role inside the clause and there is none left. What the clause supplies is a location, so the slot takes where. In that means because and produces nonsense here. Answer (B).
Mẹo kiểm nhanh: đọc riêng mệnh đề sau chỗ trống. Nếu nó đã đủ chủ ngữ và đủ tân ngữ thì chỗ trống không thể là which/that/who — phải là where, when, hoặc whose + danh từ. Nếu nó thiếu chủ ngữ thì chỗ trống chính là chủ ngữ, tức who, which hoặc that.
Names and other one-of-a-kind nouns
A proper noun, or any noun already made unique by the sentence, cannot be narrowed further. Any relative clause attached to it is automatically non-restrictive and automatically needs a pair.
The mirror image also holds: after the only, the first, the sole, or a superlative, the clause is doing the identifying and must be restrictive.
Lise Meitnercalculations explained the fission results her former collaborator published in 1939was omitted from the Nobel citation.
- whose\ …\ ,
- , whose\ …\ ,
- , whose\ …\ (none)
- whose\ …\ (none)
Lise Meitner is already a unique person, so the whose clause is a supplement and needs a comma to open it as well as one to close it. (A) opens nothing; (D) closes nothing and leaves was omitted adrift; (C) opens without closing. Test the deletion: Lise Meitner was omitted from the Nobel citation is complete. Answer (B).
Bẫy nặng nhất của cả nhóm câu: chỉ có một chỗ trống hiện ra nhưng dấu mở đã nằm sẵn trong đề. Học sinh nhìn chỗ trống rồi chọn “không dấu” cho gọn, trong khi câu đã mở cặp từ trước và đang thiếu vế đóng. Cứ thấy một dấu phẩy hoặc một gạch ngang lơ lửng phía trước chỗ trống là phải tìm vế đóng.
The same rule covers appositives and participles
An appositive (a songbird that nests only in young jack pine) and a reduced participial phrase (recovered from a shipwreck in 1901) behave exactly like relative clauses: delete, then decide, then match the pair.
Kirtland's warblera songbird that nests only in stands of young jack pinewas among the first species protected under federal law.
- —\ …\ ,
- ,\ …\ —
- ,\ …\ ,
- (none)\ …\ (none)
The middle phrase renames a species that the sentence has already named, so it is a supplement. (A) and (B) each pair a dash with a comma. (D) runs the appositive straight into the subject and then into the verb was, producing a subject the reader cannot close off. Answer (C).
The techniquethat Renaissance painters used to build translucent skin tonesrequired as many as forty separate glazes.
- ,\ …\ ,
- (none)\ …\ (none)
- ,\ …\ (none)
- (none)\ …\ ,
The technique on its own names nothing in particular; the that clause is what identifies it, so the clause is restrictive and takes no punctuation. The closing blank is the harder half: it sits between the whole subject and the verb required, and nothing may separate a subject from its verb. Answer (B).
Hai chỗ trống trong một câu gần như luôn là câu hỏi về cặp đóng mở. Có đúng bốn khả năng hợp lệ: hai phẩy, hai gạch ngang, hai ngoặc đơn, hoặc không dấu nào cả. Mọi phương án trộn hai loại đều sai, kể cả khi nghe rất xuôi tai. Nếu đề chỉ cho một phương án khớp cặp thì đó là đáp án, khỏi cần đọc nghĩa.