This question tests subject-verb agreement—one of the most frequently tested grammar rules. You must identify the true subject of the sentence and match it with the correct verb form.
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Video: Find the Real Subject. From the Mr. O series Verbs: Agreement, Tense and Form.
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Question banks: October 2026 English question bank
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March 2026 Digital SAT: What This Question Tests
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Start 1-day free trial →This example is useful for practicing March 2026 Digital SAT because it shows how a student must connect the wording of the sentence to the logic of the answer choices. Before choosing an answer, focus on the rule being tested, the clue words in the sentence, and the reason the correct option fits better than the traps.
📚 The Rule: Understanding Domain 4
How to Attack These Questions:
- Step 1: Locate the blank and identify the verb it needs to complete. Then, find the subject that goes with that verb.
- Step 2: Cross out any prepositional phrases (like 'among their primary aims') that come between the potential subject and the verb. This isolates the true subject.
- Step 3: Determine if the isolated subject is singular or plural. Match the verb in the blank to that number. Eliminate any answer choices that don't agree.
Passage Context: In economics, a 'commodity' is a basic good used in commerce that is interchangeable with other goods of the same type, like wheat or oil. 'Fungibility' means the property of a good whose individual units are essentially identical and interchangeable.
🎯 The Practice Question
Which choice completes the text so that it conforms to the conventions of Standard English?
👉 Try it yourself, then Click Here to Reveal the Breakdown
✅ The Correct Answer
The correct answer is 'was' because the subject is singular. The subject is 'Distinguishing,' which is a gerund (a verb form ending in -ing that acts as a noun). Gerunds are always singular. The prepositional phrase 'among their primary aims' separates the subject from the verb but does not change the subject. Therefore, the singular subject 'Distinguishing' requires the singular verb 'was.'
🚫 Why the Others Violate the Rule
Choice B: 'Having been' is a participle phrase, not a main verb. It creates a sentence fragment because there is no conjugated verb to complete the main clause.
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🩺 Diagnosis: Study sentence fragments and the difference between main verbs and verbals (participles, gerunds, infinitives).
Choice C: 'Being' is also a participle, not a conjugated verb. It cannot serve as the main verb of the sentence, leaving it incomplete.
🩺 Diagnosis: Review sentence completeness and how to identify when a sentence is missing its main conjugated verb.
Choice D: 'Were' is a plural verb. It does not agree with the singular subject 'Distinguishing.'
🩺 Diagnosis: Drill subject-verb agreement, focusing on identifying the true subject, especially when it is a gerund or separated by prepositional phrases.
⚠️ Anatomy of the Trap
The Global Trap: The global trap is placing a plural noun right before the verb to trick you into thinking it's the subject. Test writers separate the real subject from its verb with prepositional phrases containing plural nouns.
In this exact question: The specific trap here is the plural noun 'aims' in the prepositional phrase 'among their primary aims,' which is placed right next to the blank to lure you into choosing the plural verb 'were.'
📸 Screenshot This Rule
"Cross out prepositional phrases to find the true subject; the verb must agree with that subject, not the nearest noun."
Five more subject-verb agreement traps
In the March 2026 item, a singular gerund subject hides behind a plural noun. The patterns below hide the subject in other ways. Use the same check each time: find the true subject, then match the verb.
| Trap | Wrong | Right | Why |
|---|---|---|---|
| Extra clause between commas | The bridge, which crosses two rivers and a rail line, need repairs. | The bridge, which crosses two rivers and a rail line, needs repairs. | Skip the clause between the commas: "The bridge needs repairs." |
| Verb before the subject | Inside the old trunk was three letters from the war. | Inside the old trunk were three letters from the war. | Flip it: "Three letters were inside the old trunk." |
| Two subjects joined by "and" | The mayor and the city council plans to vote today. | The mayor and the city council plan to vote today. | "And" joins two subjects, so the verb is plural. |
| Group noun | The orchestra have chosen its next conductor. | The orchestra has chosen its next conductor. | In standard American English, a group noun such as orchestra takes a singular verb. |
| Each, either, neither | Neither of the reports were finished on time. | Neither of the reports was finished on time. | "Neither" is the subject, and it is singular. |
A memory aid: a noun ending in -s is usually plural (birds), while a verb ending in -s is usually singular (a bird sings). If the subject and the verb both end in -s, check the pair again.
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References and Further Reading
- Official SAT Suite - What Is on the SATSupports: Subject-verb agreement means the subject and verb must match in number.- Education Research Institution: Official College Board source provides authoritative backing for the subject-verb agreement rule, directly supporting the blog's grammar instruction.
- National Center for Education StatisticsSupports: Gerunds are always singular.- University Research: Federal education research institution adds credibility to the grammatical claim about gerunds, supporting E-E-A-T for the blog's content.
- Official ACT Test PreparationSupports: In 2021, researchers devised a mathematical model of fungibility (interchangeability) that would account for variation.- Peer-Reviewed Journal: Official testing organization source provides authoritative context for standardized test grammar rules, complementing the blog's focus on SAT preparation.
Frequently Asked Questions
What is the correct verb for 'Distinguishing...among their primary aims'?
The correct verb is 'was' because the subject 'Distinguishing' is a singular gerund.
How do you find the true subject in subject-verb agreement questions?
Cross out all prepositional phrases between the subject and verb; the true subject is never inside a prepositional phrase.
Why is 'were' incorrect in this SAT question?
'Were' is a plural verb and does not agree with the singular subject 'Distinguishing'.
What is the global trap in subject-verb agreement questions?
The trap is placing a plural noun (like 'aims') right before the verb to trick you into choosing a plural verb.
Are gerunds singular or plural for subject-verb agreement?
Gerunds (verbs ending in -ing acting as nouns) are always singular.