Q: Would you ever use “Who are …” in a question? I always say “Who is …” even if I know the answer will be plural. For example, I’d say, “Who’s coming to dinner?” and not “Who are coming to dinner?”
A: We found an interesting juxtaposition of “who is” and “who are” in an old book, Richard Marsh’s Frivolities (1899). One character says, “It is they who are coming,” and the other replies, “And pray who is coming?”
The convention here is that in an interrogative sentence—one that asks a question—“who” (as well as “what”) is generally used with a singular verb, even when it’s understood that the pronoun refers to more than one person (or thing).
If the sentence were turned around and made declarative (that is, a statement rather than a question), a pronoun understood to be plural would be used with a plural verb.
That’s why we say things like “Who is [singular] complaining?” … “They’re the people who are [plural] complaining.” And “Who is [singular] at that table over there?” … “You must mean my neighbors, who are [plural] at the table by the door.”
As Bergen Evans and Cornelia Evans write in A Dictionary of Contemporary American Usage, “An interrogative pronoun is usually treated as a singular. That is, we may say who is coming? and what is in the box? regardless of how many people or things are to be expected.”
Note the word “usually” there, because this is not a universal rule with interrogative pronouns. The interrogative “who” is used with a plural verb, for instance, when plural elements are present. Examples: “Who are they?” … “Who are your favorite authors?”
The Evanses’ guide, by the way, was first published in the 1950s, but it’s still “contemporary” and sensible, and it’s worth picking up if you spot it in a sale of old books.
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