An agreement question tests whether a verb matches its subject despite extra words between them. At the blank, sort the forms into singular, plural, and forms that can't be main verbs alone. Then find the true subject by crossing out phrases and extra information. In the present tense, one thing takes the -s form, is, or has; more than one takes the plain form, are, or have. Check with it or they, because nearby nouns may not be the subject.
Hints
- Hint 1
Read to the period and check whether the opening subject already has a main verb. Does served belong to that subject or to the part about the vessel?
- Hint 2
Look at how the labels are attached to the opening noun. Do the words introducing them join two subjects, or add extra information?
- Hint 3
Cross out the describing phrases and the words between commas. Which noun is left, and would you replace it with it or they?
Step-by-step
Sort, find the subject, and match
Step 1Sort the verb forms
Start by sorting the verb forms: in this sentence, indicate and have indicated go with more than one, while indicating can't be a main verb without a helper such as is. A main verb says what the subject does or is. Does this sentence already have one for its opening subject? The verb in that the vessel served belongs to the part about the vessel, so it doesn't fill that job. The blank needs a main verb, which rules out indicating.
- Step 2
Uncover the true subject
What points to the vessel's use as a measuring cup? Cross out together with three inked labels identified by conservators during infrared imaging, the extra words set off by commas right before the blank. The words together with add information, but they don't join two subjects the way and does. Next, cross out of tiny notches along the rim of a 2,000-year-old clay vessel, which tells us what the sequence contains and where it is. That leaves A sequence as the true subject of the verb.
- Step 3
Match one sequence to its verb
A sequence is one thing, even though it contains many notches, so its verb must be singular. Which form matches when we replace that subject with it? It indicate and it have indicated don't match, because neither verb form agrees with it. The singular form indicates passes that check: it indicates. Choice A.