The delete test comes first
A supplement is material the sentence does not need in order to be a sentence. Before choosing a mark, delete the material and read what is left.
Three outcomes. If the remainder is a complete sentence with the same meaning, the material is a supplement and takes an enclosing pair. If the remainder is complete but says something different or no longer identifies which one, the material is essential and takes nothing. If the remainder is not a sentence at all, the material is not a supplement and the whole item is about something else.
The observatory's original mirrorcast in 1897 and never replacedhas a chip near its outer edge.
- ,\ …\ —
- —\ …\ ,
- ,\ …\ ,
- (\ …\ ,
Delete the participial phrase: The observatory's original mirror has a chip near its outer edge. Complete, same meaning, so the phrase is a supplement and needs an enclosing pair. Three of the four choices open with one mark and close with a different one. Answer (C).
The tunnel engineerswho had worked below the water table beforewere assigned to the eastern shaft; the rest stayed on the surface.
- (none)\ …\ (none)
- ,\ …\ ,
- —\ …\ —
- (\ …\ )
The rest at the end of the sentence proves that only some of the engineers went to the eastern shaft. The relative clause is what divides them, so deleting it changes the claim and leaves the rest with nothing to be the rest of. The clause identifies which engineers, so it is essential and takes no punctuation. Three matched pairs are on offer and all three are wrong for the same reason. Answer (A).
Đề rất hay bày ra hai, ba cặp khớp cùng lúc để dụ. Đừng nhìn cặp trước. Xoá cụm ở giữa đi rồi đọc lại câu: nếu nghĩa đổi hoặc câu không còn chỉ rõ đang nói về cái nào, thì cụm đó là thông tin xác định, và mọi cặp dấu — phẩy, gạch ngang hay ngoặc đơn — đều sai như nhau.
The pair must match
Two commas, two dashes, or two parentheses. Never one of each. A comma opening and a dash closing reads smoothly and is wrong every time.
The atlasprinted in Antwerp in 1570 and reissued more than forty timesfixed the shape of the continents in the European imagination for a century.
- ,\ …\ —
- —\ …\ —
- —\ …\ ,
- (\ …\ —
The phrase is deletable, so it is a supplement. Only one of the four choices uses the same mark at both ends. Answer (B).
Khi cụm xen dài, mắt đọc tới cuối đã quên mất đầu câu mở bằng dấu gì. Cách chữa duy nhất là quay ngược lại nhìn dấu ở đầu cụm trước khi chọn dấu đóng — và nếu một trong hai đầu đã in sẵn trong đề thì đầu kia đã bị quyết định xong, không còn gì để cân nhắc.
Which pair to choose
All three pairs are grammatically legal around the same supplement. They differ in emphasis: dashes push the material forward, parentheses push it back, commas are neutral. A test item therefore never offers two legal matched pairs at once — if it seems to, one of them is mismatched somewhere.
Nansen's shipthe Framwas built with a rounded hull so that pressure from the ice would lift it rather than crush it.
- —\ …\ ,
- ,\ …\ (none)
- ,\ …\ ,
- (none)\ …\ ,
The name is an appositive supplement, and only (C) opens and closes with the same mark. (B) and (D) leave a single comma standing between the subject and its verb, which is an error even when the material is a supplement. Answer (C).
When only dashes will do
If the supplement contains commas of its own, the enclosing pair must be dashes. Commas at the boundaries would be indistinguishable from the commas inside, and the reader would count the wrong number of items.
The three species that survived the bottlenecka finch, a gecko, and a land snailare all found nowhere else.
- ,\ …\ ,
- ,\ …\ —
- (none)\ …\ (none)
- —\ …\ —
The supplement is itself a three-item list with internal commas. Enclosing it in commas, as in (A), produces a string of commas in which the boundary of the supplement disappears. (B) does not match, and (C) leaves the list jammed between subject and verb. Answer (D).
Đây là luật dễ nhớ nhất và cũng dễ quên nhất: cụm xen mà bên trong đã có dấu phẩy thì bắt buộc kẹp bằng hai gạch ngang. Không phải vì gạch ngang “mạnh hơn”, mà vì nếu dùng phẩy thì người đọc không biết dấu phẩy nào là ranh giới cụm và dấu phẩy nào là ranh giới các mục bên trong.
The single dash, and punctuation around parentheses
A dash also works alone. After a complete clause, one dash can introduce a list, an appositive or an explanation, much as a colon does.
The dig produced one object that no one could explaina bronze gear train wrapped in corroded wood.
- ;
- —
- .
- and
The left side is a complete sentence; the right side is a noun phrase with no verb, so a semicolon or a period would strand a fragment, and and would make the gear train a second object produced, contradicting one object. A single dash introduces the appositive. Answer (B).
Parentheses take the sentence's own punctuation outside the closing bracket. The material inside never carries a comma that belongs to the main sentence.
Although the technique was published in 1954in a journal that folded two years laterit was not widely adopted until the 1980s.
- (\ …\ ,)
- ,\ (\ …\ )
- (\ …\ ),
- (\ …\ )
The opening Although… clause needs a comma before the main clause, and that comma belongs to the sentence, not to the parenthetical, so it goes after the closing bracket. (A) traps it inside; (B) puts it before the opening bracket, where it separates nothing; (D) omits it and runs the dependent clause into the main clause. Answer (C).
Ngoặc đơn không xoá được nhiệm vụ dấu câu của câu chính. Nếu bỏ hẳn phần trong ngoặc ra mà câu vẫn cần một dấu phẩy ở chỗ đó, thì dấu phẩy ấy vẫn phải có — và nó đứng sau ngoặc đóng. Nhốt nó vào trong ngoặc là sai.
Gạch ngang đơn ở cuối câu hoạt động gần như dấu hai chấm: bên trái phải là câu đủ, bên phải có thể là danh sách, cụm đồng vị hay lời giải thích. Khác biệt duy nhất nằm ở sắc thái, nên đề không bao giờ đặt gạch ngang đơn và dấu hai chấm cạnh nhau trong cùng một câu hỏi — thấy gạch ngang đơn là hỏi ngay “bên trái đã thành câu chưa”, chứ không hỏi “có trang trọng không”.