Detect Error in Sentence

Why this topic is worth your marks

Detect-the-error questions appear in almost every AFCAT English section, usually as three to five questions. They are pure rule-testing: no vocabulary memorisation, no comprehension reading — just grammar you already half-know. That makes them among the fastest scoring questions on the paper if your basics are tight. A candidate who has drilled twenty core rules can finish all of them in barely two minutes, freeing time for the heavier reading-comprehension passages.

The format is simple. A sentence is divided into labelled parts (often A, B, C, D). You must pick the part containing the error. A fifth option, usually “No error”, is genuinely correct in a meaningful share of questions, so never rule it out. Examiners deliberately add a few flawless sentences to catch candidates who assume an error must exist.

Because AFCAT carries negative marking, accuracy matters as much as speed here. The good news is that these questions test a small, predictable set of rules. Once you can name the rule a segment is testing, the answer almost chooses itself. Treat this chapter as a checklist you internalise rather than a topic you merely read.

The segment-by-segment method

Random reading wastes time and lets the “sounds right” instinct fool you. Use a fixed sweep instead. First read the whole sentence once for meaning — you cannot judge agreement or tense without knowing what the sentence is trying to say. Then check each labelled part against this short list, in order.

1. Verb — does it agree with its subject in number and person?
2. Tense — is the time-frame consistent across the sentence?
3. Preposition — is the right one used after the verb/adjective?
4. Article & noun — is a/an/the correct, and the noun count right?
5. Pronoun — does it match its noun and case?

This order is deliberate: it runs from the most-tested error type (agreement) down to the least. By the time you reach the bottom of the list you will usually have already found the mistake, so most questions take only a few seconds. The discipline of always sweeping in the same order is what separates a confident scorer from a candidate who second-guesses every option.

Subject-verb agreement: the No. 1 error zone

This is the most heavily tested area. The verb must match the real subject, not the nearest noun.

Watch collective nouns too. Words like team, jury, committee, family, government usually take a singular verb when acting as one unit (The team is winning). They turn plural only when the members are clearly acting individually, which AFCAT rarely tests, so default to singular.

A second tricky group is the “number” pair. A number of students are… takes a plural verb, but The number of students is… takes a singular verb. Likewise, expressions of distance, money or time treated as a single amount take a singular verb: Ten kilometres is a long walk; five hundred rupees is enough.

Tense and time-frame errors

Examiners love a sentence where one clause silently switches tense. Keep the time-frame consistent unless the meaning genuinely shifts. The classic trap is a sentence that starts in the past and slips into the present, or vice versa, in a later segment — that later segment is your error.

Preposition and usage traps

Prepositions follow fixed collocations that you must simply know — there is little logic to memorise, only patterns to absorb through practice. AFCAT tests the high-frequency ones repeatedly, so a short list goes a long way.

• Differ from a thing, but differ with a person.
• Comprise takes no “of” — The team comprises ten players.
• Married to, not married with; superior to / inferior to, never “than”.
• Discuss, enter, resemble, request, order, reach take no preposition: Discuss the matter, not “discuss about”.
• Accompanied by, accused of, confident of, capable of, devoid of — the fixed partner never changes.
• Prevent from, prohibit from, refrain from — all pair with from.

Articles, nouns and number

Article and noun-number errors are easy marks once you know the rules, yet they trip up candidates who rely on the spelling of the next word instead of its sound. The choice between a and an depends on pronunciation, not the first letter.

Pronoun, adjective and adverb slips

A second tier of common errors involves the smaller words that link a sentence together. These slip past your ear easily, so they reward a candidate who checks them deliberately rather than by feel.

• Case: use between you and me (object form), never “between you and I”.
• Comparatives: use -er / more for two things, -est / most for three or more. Avoid double comparatives like “more better”.
• Adjective vs adverb: a verb is modified by an adverb — She sings well, not “sings good”.
• Less vs fewer: fewer for countables (fewer cars), less for uncountables (less water).

Speed shortcuts for under 30 seconds

Trained candidates do not check every word with equal care. They scan for high-yield trigger signals first — small words that almost always flag a particular rule the examiner is testing. Spotting the signal tells you exactly which rule to apply, so you skip straight to the likely error.

• Spot a since / for → instantly check for present perfect.
• Spot each, every, one of, neither → instantly check the verb is singular.
• Spot a long phrase between subject and verb → mentally delete it and re-check agreement.
• Spot back, again, return, repeat, comprise, discuss → check for a redundant or wrong preposition.

Worked example

The trap was the nearby plural “students”. The real subject is the singular “One”, so the main verb must be singular. Notice that the relative-clause verb (“were present”) is a separate matter and agrees with its own subject — never confuse the two verbs in such sentences.

A few more classic traps

Keep these tested patterns ready — they recur across AFCAT papers and reward the candidate who recognises the structure instantly.

• Hardly / scarcely…when and no sooner…than — pairing the wrong connector is an error.
• Not only…but also must keep parallel structure on both sides.
• The reason is because is wrong → use the reason is that.
• Cope with, prefer to, consist of — learn the fixed partner word.
• Either / neither refer to two; for three or more use any / none.
• Lest…should — Work hard lest you should fail; never add “not” after lest.

Most of these are testing the same idea: a fixed expression has a fixed partner word, and the error is the segment that swaps that partner for a wrong one. When you see the first half of such a pair, your eyes should jump straight to the second half to confirm it matches.

Previous-year style question

Note how the same rule from our agreement section reappears in a real-paper format. Master a handful of rules and you cover most of what AFCAT can ask. The examiner is not inventing new traps each year — the same patterns rotate, so disciplined practice with previous papers builds genuine confidence and speed.

Quick revision