An agreement question tests whether a verb matches its subject: one thing takes a singular verb, and more than one takes a plural verb. First, sort the verb forms by number, trying each after it and they. Ask who or what the verb is about, and cross out phrases and extra information to find its true subject. Nearby nouns inside those phrases don’t decide the verb’s number, even when they sit right beside the blank.
Hints
- Hint 1
Look at the words before the blank. Which ones name what’s on display, and which ones only describe it?
- Hint 2
Cross out the phrase beginning with of and the words between commas. Can you replace the remaining subject with it or they?
Step-by-step
Sort, find, and match
Step 1Sort by number
Sort the choices by number, because agreement means the verb matches whether its subject is one thing or more than one. Which forms work with they? The forms are, have been, and were do, so these need a plural subject, more than one thing. Next, ask what’s on display.
- Step 2
Find the true subject
What’s on display, and which words only describe it? The phrase of rare stamps tells us what the collection contains, while amassed over several decades tells us how it was built up. Cross out both phrases, and The collection is left before the blank. The collection is the true subject, so the stamps inside it don’t decide the verb’s number.
- Step 3
Match one collection
A collection counts as one thing, even when it contains many stamps. Can we check it with it or they? Replace The collection with it: we say it is on display, so we need a singular verb, a form for one thing. The form is matches it and completes the sentence. Choice C.