What You'll Learn This Hour
- Identify and correct subject-verb agreement errors even when prepositional phrases obscure the true subject
- Apply parallelism rules to lists, comparisons, and correlative conjunctions (not only … but also)
- Place modifiers correctly so that dangling and misplaced modifiers are immediately recognizable
- Eliminate pronoun ambiguity and tense inconsistency — two of the most commonly tested SC traps
Core Concepts
Subject-Verb Agreement
The verb must agree with the real subject, not with nouns in prepositional phrases that come between them. Strip away everything between the subject and verb, then check agreement.
The quality of the proposals were disappointing.
The quality of the proposals was disappointing.
Key triggers: "of," "along with," "as well as," "together with" — none of these change the subject.
Parallelism
All items in a list or comparison must share the same grammatical form. If the first item is an infinitive, every item must be an infinitive.
She likes to run, swimming, and to cycle.
She likes to run, to swim, and to cycle.
Parallelism signals: and, but, or, not only … but also, both … and, either … or, neither … nor.
Modifier Placement
A modifier must be placed directly adjacent to the word it modifies. An opening participial phrase modifies the subject of the main clause.
Running down the street, the bus was missed by Maria.
Running down the street, Maria missed the bus.
Rule: The subject of the main clause must be the logical performer of the opening modifier.
Pronoun Reference
Every pronoun must have a clear, unambiguous antecedent and must agree with it in number. Collective nouns (company, government, team) are singular.
When the manager met the director, he approved the plan. (Who approved it?)
When the manager met the director, the director approved the plan.
Verb Tense Consistency
Tense must be logically consistent throughout a sentence. Use the simple past for a completed action; use the past perfect (had + past participle) only when one past action clearly preceded another.
By the time the auditors arrived, the CFO destroyed all the records.
By the time the auditors arrived, the CFO had destroyed all the records.
SC Error Frequency on the GMAT
Based on analysis of official GMAT practice questions — know where the points are.
Subject-Verb and Parallelism together account for over half of all SC errors
Worked Examples
Question: "The board of directors, along with the CEO and three senior executives, [have / has] approved the new restructuring plan."
Step-by-Step Solution:
Step 1: Identify the subject. Ignore "of directors" (prepositional phrase) and "along with the CEO and three senior executives" (not a true compound subject).
Step 2: The true subject is "The board" — a singular noun.
Step 3: "Along with" functions like a parenthetical; it does NOT create a plural subject the way "and" would.
Step 4: A singular subject requires a singular verb: has.
Answer: "has approved" — The board … has approved the plan.
Question: "The consultant recommended cutting costs, to increase revenue, and that the company should hire new talent."
Step-by-Step Solution:
Step 1: Spot the list — three things are recommended: "cutting costs," "to increase revenue," "that the company should hire."
Step 2: These are three different forms: gerund, infinitive, noun clause. Parallelism requires identical structure.
Step 3: Anchor the list in one form. Gerunds work best here: cutting, increasing, hiring.
Step 4: Rewrite: "The consultant recommended cutting costs, increasing revenue, and hiring new talent."
Answer: All three items must be gerunds — cutting, increasing, hiring.
Question: "Having studied the market for over a decade, the report was written by the analyst to persuade investors."
Step-by-Step Solution:
Step 1: Identify the opening modifier: "Having studied the market for over a decade."
Step 2: Ask: who studied the market? The analyst — not the report. The report cannot study anything.
Step 3: This is a dangling modifier. The subject of the main clause (currently "the report") must be the performer of the modifier.
Step 4: Fix by making the analyst the subject: "Having studied the market for over a decade, the analyst wrote the report to persuade investors."
Answer: Restructure so the analyst is the main clause's subject.
GMAT Traps to Avoid
Trap 1: Prepositional phrases between subject and verb
Phrases beginning with "of," "in," "on," "with," "among," "between" separate the subject from its verb visually but have zero effect on agreement. Always isolate the subject first.
Example: "The results of the five-year study show…" — subject is "results" (plural), not "study."
Trap 2: "Being" is almost always wrong
"Being" is one of the most reliable wrong-answer signals on the GMAT. It creates passive, wordy constructions. If an answer choice contains "being," eliminate it unless every other option is clearly worse.
Wrong: "The contract being signed by both parties…" — Prefer: "The contract signed by both parties…"
Trap 3: Compare like to like
Comparisons must be logically parallel. You cannot compare a country to an economy, or a person to an event. The entities being compared must be the same type of thing.
Wrong: "France's GDP is higher than Germany." → Correct: "France's GDP is higher than Germany's."
Trap 4: Collective nouns are singular
Words like government, committee, jury, company, team, faculty, and board are singular on the GMAT. They take singular verbs and singular pronouns (it, its — not they, their).
Practice Questions
12 GMAT-style SC questions covering all five grammar rules. Click "Show Answer" for a full explanation.
The number of students who enroll in advanced science programs [Answer Choice] over the past decade.
Show Answer
Correct Answer: (B) has risen significantly
Why (B): "The number of" is a fixed expression that is always singular. Even though "students" is plural, the subject is "The number." Singular subject → singular verb "has risen." "Over the past decade" signals present perfect.
Why not (A)/(D): "have risen" / "have been rising" are plural — incorrect for singular "the number."
Why not (C): Present progressive suggests ongoing action right now, not a past-to-present span.
Why not (E): Past progressive suggests interrupted action, wrong for a decade-long trend.
Neither the manager nor the employees [Answer Choice] aware of the regulatory change.
Show Answer
Correct Answer: (C) were
Why (C): With "neither … nor," the verb agrees with the closer subject (the one right before the verb). Here, "the employees" is plural → "were."
Why not (A): "was" is singular, but the closer noun "employees" is plural.
Why not (B): "is" is present tense — no signal supports that here, and it's also singular.
Why not (D): "has been" is singular and present perfect — number and tense both wrong.
Why not (E): "Being" without an auxiliary is a fragment — never a standalone verb.
The committee, comprised of five economists and three policy experts, [Answer Choice] its final report last Tuesday.
Show Answer
Correct Answer: (A) submitted
Why (A): "The committee" is singular (collective noun). "Last Tuesday" signals a completed past action → simple past "submitted." Agreement: singular verb with singular subject.
Why not (B): "have submitted" is plural present perfect — both number and tense are wrong.
Why not (C): "submit" is present tense — contradicts "last Tuesday."
Why not (D)/(E): Progressive tenses imply an ongoing action interrupted or happening now, not a completed event.
The CEO stated that the company would focus on expanding its market share, to reduce operational costs, and improving employee retention.
Show Answer
Correct Answer: (B) expanding … reducing … improving
Why (B): All three items are gerunds (-ing), perfectly parallel. "Focus on" takes a gerund object, making gerunds the natural anchor form.
Why not (A): Mixes gerund, infinitive, and gerund — breaks parallelism.
Why not (C): "Focus on to expand" is unidiomatic — "focus on" requires a gerund, not an infinitive.
Why not (D): Mixes infinitive and gerunds.
Why not (E): Three different forms — noun phrase, gerund, infinitive.
Not only did the merger increase the firm's valuation, but it also [Answer Choice] its competitive position in emerging markets.
Show Answer
Correct Answer: (C) strengthened
Why (C): "Not only … but also" requires parallel structure. The first clause uses the simple past "did … increase" (main verb "increase"). The second clause needs the same verb form: "strengthened" (simple past, matching "did increase" = increased).
Why not (A): "Strengthening" is a participle — creates a fragment after "also."
Why not (B): "To strengthen" is an infinitive — not parallel to past tense.
Why not (D): "Has strengthened" (present perfect) shifts tense without reason.
Why not (E): Noun phrase — not parallel to a past-tense verb.
The new policy requires managers to document all decisions, [Answer Choice] regular performance reviews, and provide written feedback.
Show Answer
Correct Answer: (B) to conduct
Why (B): "Requires managers to document … to conduct … and [to] provide" — all three items are infinitives. "Requires … to" establishes the infinitive pattern. "To" before "provide" is implied but understood.
Why not (A)/(D)/(E): Non-infinitive forms break parallelism with "to document" and "provide."
Why not (C): "conduct" (bare infinitive) without "to" is not parallel to the explicit "to document" that opens the list.
Praised by critics for its nuanced narrative, [Answer Choice].
Show Answer
Correct Answer: (C) the film nonetheless failed at the box office
Why (C): The opening phrase "Praised by critics" must modify the subject of the main clause. Only "the film" makes logical sense — the film was praised. "The film" immediately follows the comma, correctly placed.
Why not (A): "The film's box-office performance" cannot be praised by critics — a performance isn't praised for narrative.
Why not (B): "Many viewers" were not praised by critics.
Why not (D): Passive construction — "a box-office run" was not praised.
Why not (E): "It" is a vague pronoun and the construction is unnecessarily wordy.
A leading authority on behavioral economics, [Answer Choice] on incentive design and decision-making.
Show Answer
Correct Answer: (C) Professor Holt has focused his research extensively
Why (C): "A leading authority on behavioral economics" describes a person — Professor Holt. He must be the subject immediately following the comma. (C) correctly places "Professor Holt" as the subject.
Why not (A): "Professor Holt's research" is possessive — the subject is "research," not Professor Holt himself. Research cannot be an authority.
Why not (B): "Extensive research" is the subject — research is not an authority.
Why not (D): "The research of Professor Holt" — same problem as (A).
Why not (E): Awkward expletive construction; wordy and the split "it was … who" is stylistically poor.
The scientist discovered a mineral sample that [Answer Choice], unlike any previously catalogued substance, an entirely new molecular structure.
Show Answer
Correct Answer: (C) had
Why (C): The main clause is past tense ("discovered"). The relative clause describes a property of the sample at the time of discovery. Past tense "had" is consistent and logical.
Why not (A): "Is having" is progressive — "have" with structural meanings (possess) doesn't use progressive aspect.
Why not (B): "Having" without a subject creates a participial phrase fragment, not a relative clause.
Why not (D): "Has" is present tense — shifts the clause to present, inconsistent with past "discovered."
Why not (E): "Being of" is the red-flag "being" construction — wordy and ungrammatical here.
When analysts compared the revenue projections of the two divisions, they found that [Answer Choice] had overestimated future demand by nearly 40 percent.
Show Answer
Correct Answer: (D) the revenue projections
Why (D): Revenue projections — not the analysts, not the divisions — overestimate demand. This is the only logically precise and unambiguous choice. Replacing a vague pronoun with a clear noun is a classic GMAT move.
Why not (A): "They" is ambiguous — could refer to analysts, divisions, or projections.
Why not (B): "It" is singular — no clear singular antecedent.
Why not (C): Divisions don't overestimate; projections do. Logically imprecise.
Why not (E): "One of the divisions" is singular and vague about which one — introduces new ambiguity.
The government announced that [Answer Choice] would be revising its trade policy in response to the new tariff framework introduced by neighboring countries.
Show Answer
Correct Answer: (B) it
Why (B): "The government" is a collective noun — singular on the GMAT. It takes singular pronoun "it" and singular possessive "its" (already in the sentence). "It would be revising its trade policy" is internally consistent.
Why not (A): "They" is plural — collective noun "government" is singular.
Why not (C): "The countries" introduces a new noun not previously mentioned as the subject doing the announcing.
Why not (D): "Those" is a demonstrative pronoun — vague and has no clear antecedent.
Why not (E): "We" is first person — no first-person voice in this sentence.
By the time the investigation concluded, the accounting firm [Answer Choice] all relevant documents and cooperated fully with regulators.
Show Answer
Correct Answer: (C) had already provided
Why (C): "By the time … concluded" signals that one past action (providing documents) was completed before another past action (the investigation concluding). Two past events in sequence → the earlier one requires the past perfect "had provided."
Why not (A): "Already provided" is simple past — doesn't show the sequence of two past events.
Why not (B): "Has provided" is present perfect — wrong tense entirely, suggests the action connects to the present.
Why not (D): "Was providing" is past progressive — implies the action was ongoing at the time the investigation concluded, not completed before it.
Why not (E): "Would have provided" is the conditional perfect — used in hypotheticals ("if … would have"), not factual statements.
Quick Reference Card
# SC Grammar Rules — Hour 14 Cheat Sheet
## SUBJECT-VERB AGREEMENT
"The number of X" → singular verb (has, was)
"A number of X" → plural verb (have, were)
"Neither A nor B" → verb agrees with B (closer noun)
"Either A or B" → verb agrees with B (closer noun)
Collective nouns (board, committee, government) → singular
## PARALLELISM SIGNALS
and / but / or → same grammatical form
not only … but also → parallel verbs
both … and / either … or / neither … nor → parallel forms
## MODIFIERS
[Opening phrase], [SUBJECT] ... ← subject must perform the action
Eliminate if subject ≠ logical doer → dangling modifier
## PRONOUNS
Ambiguous "they/it/he/she" → replace with specific noun
Company/government/board → "it/its" NOT "they/their"
## TENSE
"By the time X occurred, Y [had done]" → past perfect
Two simultaneous past actions → both simple past
Established/scientific facts → simple present always
## ELIMINATE IMMEDIATELY
"being" as main verb → wrong 95% of the time
Pronoun with two possible antecedents → wrong
Comparing noun to possessive → wrong (France vs France's)