Each, every, either: the words that look plural and are not
"Each of the museums has digitized their archive." The pronoun is plural. The thing it stands for — each museum, one at a time — is singular.
Why it happens
The plural noun sits right next to the pronoun ("of the museums"), and the actual antecedent, "each", is further away and does not look plural to the ear. Distance loses to proximity every time you are reading quickly.
See the trap
"Each of the museums has digitized ___ archive of nineteenth-century maps."
✗ The trap: "their archive" — a plural pronoun matched to the nearby plural "museums".
✓ The fix: "its archive" — the antecedent is "each", which is singular. Note the verb agrees the same way: "has", not "have".
How to actually fix it
- Circle the antecedent — the word the pronoun stands for, not the nearest noun.
- Each, every, either, neither, and the -one/-body words are singular, however plural the phrase after them looks.
- Check the verb at the same time; it agrees with the same word the pronoun does.
Made this mistake on a real question?
Practice Standard English Conventions questions here. Miss one and it is logged with the exact error, then brought back until you beat it.
Practice Standard English Conventions →FAQ
Does this mean "each student ... their" is wrong?
That is a different and contested case, and it is not what this page is about. Singular "they" for a person is standard English and widely accepted, so the SAT does not build questions that hinge on rejecting it. The agreement questions you will actually see use antecedents like the one above, where no one disputes that "its" is the match.
What about a collective noun like "the committee"?
In American usage a collective noun is singular: "The committee released its findings." Use a plural pronoun only when the sentence is clearly about the members acting separately, and even then rewriting to "the committee members" is cleaner.
How do I stop repeating this mistake?
Reading the explanation isn't enough — your brain needs to beat the trap on a fresh question. Practice the skill in the kaoshen.co question bank: miss one and it is logged with the exact error, then brought back to you three days later and again after fourteen.