Architects in ancient Rome achieved remarkable structural durability by mixing volcanic ash with slaked lime. This specific volcanic ash _______ was sourced primarily from the region around Mount Vesuvius and contained reactive silica and alumina. When mixed with water, the combination triggered a chemical reaction that formed a mineral called stratlingite, which prevented the spread of microscopic cracks throughout the concrete.
Which choice completes the text so that it conforms to the conventions of Standard English?
- A—known as pozzolana,
- B, known as pozzolana—
- —known as pozzolana—Cevap
- D, known as pozzolana
Cevap
The correct answer is the option that sets off the nonessential phrase with matching em dashes ('—known as pozzolana—').
The phrase 'known as pozzolana' is a nonessential appositive that provides extra, nonessential information about the volcanic ash. To conform to the conventions of Standard English, nonessential elements must be set off from the rest of the sentence using a matching pair of punctuation marks. The correct punctuation uses matching em dashes at both the beginning and the end of the phrase, properly isolating it.
Adım Adım Çözüm
Anahtar Kavram
Punctuation of Nonessential Elements