SAT OwlQuestion bank / Form, Structure, and Sense
Each fall, millions of monarch butterflies fly from Canada and the United States to forests in central Mexico, where they spend the winter. The migration of these insects across thousands of kilometers ______ one of the longest insect migrations on Earth.
Which choice completes the text so that it conforms to the conventions of Standard English?
are
is
were
have been
Show answer and explanation
Answer: B
The subject of the second sentence is "migration," which is singular; "of these insects across thousands of kilometers" is a prepositional phrase that doesn't change the number of the subject. A singular subject takes the singular verb "is." The present tense also matches the rest of the text, which describes something that happens every year.
Choice A agrees with "insects" or "kilometers," but those nouns are inside prepositional phrases and are not the subject.
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