The words between the subject and the verb are a decoy
"A collection of rare manuscripts ___ housed in the east wing." If you wrote "are", the decoy worked: the subject is "collection", not "manuscripts".
Why it happens
You match the verb to the nearest noun because that is the last one you read. The SAT places a plural noun immediately before the blank precisely so proximity fights grammar — and proximity usually wins.
See the trap
"A collection of rare manuscripts ___ housed in the east wing."
✗ The trap: "manuscripts are housed" — agreeing with the noun inside the prepositional phrase.
✓ The fix: "A collection ... is housed" — the subject is singular; "of rare manuscripts" is just a modifier.
How to actually fix it
- Cross out every phrase that starts with of, in, on, with, along with, as well as, or including.
- Read the shortened sentence: subject, then verb, nothing between them.
- Pick the verb that fits that shortened version.
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 "as well as" make a singular subject plural?
No. "The director, as well as the producers, was present." Only "and" creates a genuinely plural subject; the rest are modifiers you cross out.
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.