In 1972, French analysts at the Pierrelatte uranium enrichment plant discovered a bizarre anomaly in uranium samples from Gabon. The proportion of the fissile isotope uranium-235 was significantly lower than the standard value found everywhere else on Earth. Further investigation revealed that the Oklo deposits ______ had actually undergone self-sustaining nuclear fission reactions approximately two billion years ago.
Which choice completes the text so that it conforms to the conventions of Standard English?
- —which contained a unique combination of physical conditions—Cevap
- B, which contained a unique combination of physical conditions—
- C—which contained a unique combination of physical conditions,
- D, which contained a unique combination of physical conditions
Cevap
—which contained a unique combination of physical conditions—
The correct answer correctly uses a pair of em dashes to set off the nonessential relative clause modifying the subject. In English, nonessential elements must be bracketed by matching punctuation marks: either two commas or two em dashes. Since the clause is followed by the main verb of the sentence, wrapping the clause in em dashes successfully maintains grammatical symmetry.
Adım Adım Çözüm
Anahtar Kavram
Punctuation of Nonessential Elements