SAT OwlQuestion bank / Form, Structure, and Sense
Ice cores drilled from Antarctica contain tiny bubbles of air trapped as snow was compressed into ice. Studying the chemical makeup of these ancient air bubbles ______ scientists to reconstruct changes in Earth's atmosphere over the past 800,000 years.
Which choice completes the text so that it conforms to the conventions of Standard English?
have allowed
allow
are allowing
allows
Show answer and explanation
Answer: D
The subject is the gerund phrase "Studying the chemical makeup of these ancient air bubbles." A gerund phrase used as a subject is singular, so it takes the singular verb "allows." The plural nouns "bubbles" and "cores" are not the subject.
Choice B agrees with "bubbles," the noun just before the blank, but the true subject is the singular gerund "Studying."
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