Question 156·Hard·Form, Structure, and Sense
The set of results from the series of complex simulations—which, according to the lead engineer, _____ the most computationally demanding tasks run during last year's trials on the lab's supercomputer—requires careful verification before publication.
Which choice completes the text so that it conforms to the conventions of Standard English?
For subject-verb agreement questions inside clauses set off by commas or dashes, first find what the relative pronoun (like "which" or "that") actually refers to, ignoring extra phrases such as "according to the lead engineer." Decide whether that noun is singular or plural, then use nearby time clues (like "last year" or "now") to choose the correct tense. Finally, eliminate choices that are the wrong number (singular vs. plural) or the wrong tense, rather than trying to pick what "sounds" best.
Hints
Find what the blank is describing
Read the sentence around the dashes and identify what "which" is referring to. Is it talking about the set of results, the series, or the simulations?
Check number: singular or plural?
Once you know what "which" stands for, ask yourself if that word represents one thing (singular) or more than one thing (plural). Your verb must match that number.
Use the time clue
Look at the phrase "last year's trials." Does that suggest something happening now, something that started in the past and continues, or something completed in the past? Choose a verb form that fits that time frame.
Eliminate mismatched choices
Cross out any choice that is the wrong number (singular vs. plural) or clearly in the wrong tense for an event tied to "last year's" trials.
Step-by-step Explanation
Locate the clause with the blank
Focus on the part of the sentence inside the dashes:
"which, according to the lead engineer, _____ the most computationally demanding tasks run during last year's trials on the lab's supercomputer"
The blank is a verb inside a nonessential (extra) clause that gives more information about something mentioned earlier.
Decide what "which" refers to (the subject)
Look just before the dash: "the series of complex simulations—which...".
Logically, the things that could be computationally demanding tasks on a supercomputer are the simulations, not the "set" or the "results." So "which" is standing in for the simulations, which is a plural idea.
Because the subject is plural, the verb in the blank must be in a plural form.
Determine the correct time (tense) for the verb
The clause describes something about "last year's trials," a finished time in the past.
That means we want a verb form that clearly places the description in the past, not in the present. Keep this in mind when comparing the answer choices:
- "are" is present tense.
- "have been" is present perfect (often suggests continuing into the present).
- "was" and the remaining choice are simple past tense.
So only the simple past forms match the time frame of "last year's trials."
Combine subject agreement and tense to choose the answer
From Step 2, we know the subject (the simulations, represented by "which") is plural, so we must not choose a singular past-tense verb.
Among the past-tense options, "was" is singular and does not agree with a plural subject. The other past-tense option is the plural form, which both matches the plural subject and fits the past-time reference.
Therefore, the correct answer is B) were.