Spotting errors is the art of reading a sentence the way an examiner does — with suspicion. Every sentence has been deliberately planted with one grammatical mistake, and your job is to locate it before the next candidate does. The skill is not literary; it is surgical.
Think of the sentence as a machine with moving parts. The subject drives the verb. The pronoun must match the noun it replaces. The tense must be consistent with the timeline. When any one part malfunctions, the machine breaks — and that break is the error.
Here is the honest picture of what NDA actually tests in this section. The paper-setters return to the same five or six grammar categories again and again, year after year:
The analogy that works in the classroom: imagine the sentence as a parade. The subject is the commanding officer at the front. The verb is the marching order — it follows the CO's rank (singular/plural), not the number of soldiers behind him. Many errors happen because students get distracted by the crowd behind the CO.
At the NDA level, you are expected to have moved past basic grammar. The traps are subtle — a "along with" phrase that looks like a second subject, a "whom" that feels correct because it follows a verb, a "was" in a hypothetical condition. If you can name the grammatical rule being violated, you will get the question right consistently. If you are guessing by "feel", you will score erratically.
One more thing: in the exam hall, do not read the whole sentence first and then re-read it. Scan for the verb first, identify the subject, check agreement — then check tense, then pronouns, then word choice. This order eliminates the error in four seconds on most questions.
The core rule is straightforward: singular subject, singular verb; plural subject, plural verb. What makes exam questions hard is that the true grammatical subject is often hidden.
Intervening phrases are the primary trap. Phrases beginning with "along with", "as well as", "together with", "in addition to", "including", and "except" are parenthetical — they do not change the number of the subject.
Contrast this with "and", which genuinely joins two subjects and usually creates a plural:
Collective nouns (army, squadron, team, committee, crew, jury) are treated as singular in formal and military contexts when the group acts as a unit:
"Every" and "each" before compound subjects joined by "and" make the whole subject singular:
"Data" is increasingly accepted as singular in formal usage. In exam contexts, especially when the question presents "was" as the correction, treat "data" as singular.
In sentences expressing hypothetical, unreal, or contrary-to-fact conditions, "were" is used for all persons — including first and third person singular.
The pattern is: If + subject + were + ..., subject + would + ...
Do not confuse this with real or possible conditions:
The test is simple: can this condition be true? If no, use "were".
"Who" is a subject pronoun (like he, she, they). "Whom" is an object pronoun (like him, her, them).
The substitution test: replace "who/whom" with "he" or "him". If "he" fits, use "who". If "him" fits, use "whom".
In "The cadets who were the most disciplined received commendations" — the pronoun is the subject of "were". Replace: "they were the most disciplined" — "they" fits, so "who" is correct.
The trap in this question was that "whom" followed "believed", making it feel like an object. But trace the clause: "the instructor believed [that] they were the most disciplined" — the pronoun is the subject of the embedded clause, so "who" is correct.
Lay vs. Lie is one of the most frequently tested confusable pairs:
| Verb | Meaning | Past Tense | Past Participle | |------|---------|------------|-----------------| | Lie (intransitive) | to recline oneself | lay | lain | | Lay (transitive) | to place something | laid | laid |
"The soldiers lay down for rest" — they reclined themselves. Intransitive. Past tense of "lie" is "lay". Using "laid" is wrong because "laid" is the past tense of "lay" (to place something), and the soldiers are not placing an object.
Affect vs. Effect: "affect" is almost always a verb (to influence). "effect" is almost always a noun (a result). "The policy affects all personnel" — verb form needed, so "affects" is correct.
When you see "a group of", "a team of", "a squadron of", "a number of" — the head noun is the collective, not the noun after "of".
"The squadron of fighter jets was deployed." — Subject is "squadron" (singular). "Jets" is part of a prepositional phrase, not the subject.
Contrast: "A number of jets were deployed." — "A number of" idiomatically takes a plural verb, even though "number" is singular. This is one fixed exception to memorise.
When you see "along with", "as well as", "together with" — cross out everything between the two commas mentally. What remains is your true subject. Then match the verb to that subject alone. Example: "The pilot, ~~along with his crew~~, [was/were]?" — cross out the phrase, you get "The pilot [was/were]" — instantly "was". This takes 5 seconds vs. the 30 seconds most candidates spend re-reading the full sentence and getting confused by "crew".
Replace "who/whom" with "he" or "him" in the clause where it appears. "He" fits → use "who". "Him" fits → use "whom". In "the cadets [who/whom] the instructor believed were disciplined" — rephrase the embedded clause: "he was disciplined" (fits) → use "who". This eliminates guessing entirely. Standard method: 40 seconds of re-reading. Substitution test: 8 seconds.
Write this ladder once and commit it: Lie → lay → lain. Lay → laid → laid. The trap is that "lay" appears in both columns — as the present tense of "lay" (transitive) AND as the past tense of "lie" (intransitive). When you see "laid" in a sentence where no object is being placed, the error is automatic — change it to "lay". Test: "soldiers laid down" — what object did they place? None. So it must be past tense of "lie" → "lay". This pattern check saves 3 steps vs. trying to recall definitions under pressure.
Whenever "every" or "each" appears before a compound subject (X and Y), lock the verb to singular immediately — no exceptions. "Every soldier and officer [was/were]?" — "every" is present, lock to singular → "was". This is a one-second decision rule. Without this rule, students see "soldier and officer" and automatically write "were", costing them the mark every time.
In any "If I/he/she was..." construction, ask: is this condition actually true right now? If the answer is no (hypothetical, wishful, contrary-to-fact), replace "was" with "were" without hesitation. "If I was the CO" — are you the CO? No. Change to "were". This eliminates the need to recall the term "subjunctive mood" under pressure. Standard approach (recalling subjunctive rules): 25 seconds. This binary question: 4 seconds.
When you see a spotting-errors question in the exam hall, run this four-step sequence in order. Do not skip steps; do not start from step 4.
Step 1 — Find the verb. Every sentence has at least one main verb. Locate it first.
Step 2 — Identify the true subject. Cross out prepositional phrases and parenthetical insertions (along with, as well as, together with, in addition to). What remains is the grammatical subject. Check agreement: singular subject → singular verb, plural → plural.
Step 3 — Check the pronoun case. If "who/whom" or "he/him/his" type pronouns appear, run the substitution test. Is the pronoun functioning as a subject or an object?
Step 4 — Check word choice. Look for classic confusable pairs: lay/lie, affect/effect, rise/raise, fewer/less, number/amount. If the verb has an object, it should be transitive. If not, use the intransitive form.
If all four steps show no error, select "No error" — but be aware that NDA papers almost always include one error. If you arrive at "No error", run through the steps one more time before confirming.
Why this question: Tests the most common NDA trap — "along with" masquerading as a compound subject.
Solving path: Locate the verb ("were"). Find the subject — apply Step 2: cross out "along with his crew members". Subject = "pilot" (singular). Singular subject requires "was". The answer is option D. Time: under 8 seconds with the CO Rule.
Why this question: Tests subjunctive mood — a category that trips up candidates who rely on "feel" rather than rules.
Solving path: Spot "If I was..." — apply the Unreal Test: is the speaker actually the commanding officer? No. Hypothetical condition → "were" is required for all persons in unreal conditionals. Answer: option C. Time: 5 seconds.
Why this question: Tests the "every + compound subject" rule, which feels wrong even when you know it.
Solving path: "Every soldier and officer" — "every" before a compound subject joined by "and" makes the subject singular. Lock to singular: "was required". Answer: option A. The distractor is that "soldier and officer" looks plural — that is exactly the trap.
Why this question: Tests the who/whom distinction in an embedded clause — the hardest pronoun question type.
Solving path: The pronoun "whom" appears. Run the He/Him swap test on the embedded clause: "the instructor believed [that] they were the most disciplined" — "they" (subject form) fits. Therefore, use "who" (subject form). Answer: option B. The trap is that "whom" follows "believed", making it feel like an object — but trace the clause structure to find the true function.
Why this question: Tests the lay/lie confusion in a military context — exactly the framing NDA favours.
Solving path: "soldiers laid down for rest" — apply the Lie-Lay ladder. Did the soldiers place an object? No — they reclined themselves. So the verb needed is "lie" (intransitive). Past tense of "lie" = "lay". Therefore "laid" should be "lay". Answer: option C.
Why this question: Tests affect/effect — a word-choice error that looks like a spelling issue but is a grammatical one.
Solving path: "effects all personnel" — is "effects" being used as a noun or verb here? It follows "which", functioning as a verb in the relative clause. A verb is needed: "affects" (to influence). "Effects" as a verb exists but means "to bring about" — it would require "effects changes", not "effects personnel". Answer: option B.
Matching the verb to the nearest noun instead of the grammatical subject. In "The squadron of fighter jets were deployed", candidates see "jets" (plural, nearest) and write "were". The subject is "squadron" (singular). Always trace back to the head noun.
Treating "along with" as "and". "The general, along with his aides, were..." feels natural because two parties are mentioned. But "along with" is parenthetical. Only "and" creates a genuinely compound subject.
Writing "was" in hypothetical "If" clauses. "If I was in charge" is accepted in informal speech, so it sounds correct. In formal grammar and in NDA questions, unreal conditions require "were". Do not trust your ear on this one.
Using "whom" wherever a verb follows. "The officer whom was selected" — "whom" follows no transitive verb here; it is the subject of "was selected". Run the He/Him test rather than defaulting to "whom" after verbs.
Confusing "lay" (past tense of lie) with "laid" (past tense of lay). Because "lay" appears in both the present column (transitive: to place) and the past column (intransitive: reclined), candidates mix them up. Anchor the memory: "laid" always has an object. If there is no object, it cannot be "laid".
Ignoring "every" and "each" as agreement triggers. When these words appear before compound subjects, students see the compound structure ("soldier and officer") and pluralise the verb automatically. The moment you see "every" or "each", the verb goes singular — no matter how many nouns follow "and".