Sentence improvement questions give you an underlined part of a sentence and four alternatives — your job is to pick the version that is grammatically correct and idiomatically natural. It looks like a guessing game, but it is not. Every CDS question hides a known, repeatable error, and once you can name the error, the right option almost selects itself.
What Sentence Improvement Tests
In the CDS & OTA English paper, the improvement of sentences block appears every year and usually carries a solid bunch of questions. You are shown a sentence with one part underlined, followed by options labelled (a) to (d). One of the options — very often (d) — is “No improvement”. You must choose the alternative that makes the sentence grammatically correct and stylistically natural, or decide that the original is already best.
What is really being tested is not a single rule but your whole stock of grammar: tense, concord, prepositions, articles, word order, degrees of comparison and idiom, all at once. That is why this section is a reliable mirror of your overall English preparation. The good news is that examiners do not invent fresh traps — they recycle a small family of error types you can learn by name.
Sentence improvement is the twin of spotting errors. In error-spotting you only locate the fault; in improvement you must also supply the correction. The diagnostic skill is identical, so practising one strengthens the other.
A Four-Step Diagnostic Method
Never read the options first — they are designed to make wrong answers look attractive. Instead follow a fixed routine so that you correct the sentence in your own head before looking at the choices.
Step 1. Read the full sentence for meaning.
Step 2. Find the subject and its verb; check concord and tense.
Step 3. Name the error type in the underlined part (preposition? article? word order?).
Step 4. Frame your own correction, then match it to the closest option.
Step 4 is the discipline that separates toppers from guessers. If you decide the correct version in advance, the options become a simple matching exercise rather than a popularity contest. When your framed answer matches no option, re-read — you have probably misread the underlined boundary or missed a second error.
Underline only what is between the markers. Many candidates lose marks by “fixing” a word that is not part of the underlined segment. The examiner can only test the part shown to you.
Error Type 1: Tense and Sequence
The most frequent improvement is a wrong tense or a broken sequence of tenses. The basic rule: when the main clause is in the past, the subordinate clause is usually also in the past.
- Wrong: He said that he will come. Right: He said that he would come.
- Wrong: When I reached the station, the train left. Right: When I reached the station, the train had left (the earlier of two past actions takes past perfect).
Two patterns are tested again and again. First, a duration with since or for needs the present perfect or present perfect continuous, not the simple present: I have been living here since 2010, not I am living here since 2010. Second, a universal truth or habitual fact stays in the present tense even after a past reporting verb: The teacher said that the earth moves round the sun.
Wrong: I am knowing the answer.
Right: I know the answer. — stative verbs (know, believe, understand, own, contain) are not used in the continuous form.
Error Type 2: Subject-Verb Agreement
Concord errors are a favourite because they have one objective answer. The verb must agree with the real subject, not with a noun that happens to sit next to it.
- The list of selected names was (not were) displayed — subject is list.
- Each of the candidates has (not have) a roll number — each is singular.
- Neither the captain nor the players were ready — proximity rule, nearer subject is plural.
As well as, along with, together with, including, besides do not change the number of the subject. The officer, as well as his men, was tired — the verb agrees with the singular officer.
Error Type 3: Prepositions and Idiom
A large share of improvement questions hinges on a single wrong preposition. English fixes the preposition by convention, so these must be learnt as set phrases.
- different from (not different than)
- superior to, inferior to, senior to (never than)
- composed of, comprises (no preposition) — The team comprises eleven players, not comprises of.
- capable of, accused of, deprived of
- married to, related to, accustomed to
- good at, surprised at, angry with a person but at a thing
When the underlined part contains a preposition after an adjective or verb, suspect an idiom error first. Ask: “What word naturally follows this?” If the option swaps that preposition, it is usually the trap or the fix.
Error Type 4: Degrees of Comparison
Comparatives and superlatives are a rich source of traps. Keep four rules ready.
- No double comparatives: more better, most cleverest are wrong. Use better, cleverest.
- Comparative with 'than', superlative with 'the': She is taller than her sister; She is the tallest in the class.
- Exclude the subject in a comparison with 'other': He is taller than any other boy in the class (not than any boy, which would include himself).
- Parallel comparison: use the…the — The higher you climb, the colder it gets.
Wrong: This is the most unique solution.
Right: This is a unique solution. — absolute adjectives like unique, perfect, complete, supreme cannot be compared.
Error Type 5: Articles and Determiners
Missing, extra or wrong articles are quick to spot once you know the system. Use a/an for a non-specific singular countable noun, the for something specific or already known, and no article for general plurals and most uncountables.
- A or an by sound, not spelling: a university (yoo sound), an hour (silent h), an MP (em sound).
- The with rivers, seas, mountain ranges, newspapers and unique things: the Ganga, the Himalayas, the sun.
- No article before languages, meals, games and most proper nouns: He plays cricket; She speaks English.
Do not use the before an abstract or material noun used in a general sense: Honesty is the best policy (not The honesty). Add the only when the noun is made specific: the honesty of the witness impressed the judge.
Determiners other than articles are tested too. Use much and little with uncountable nouns and many and few with countable plurals: much water, many books. Remember the meaning shift between few (almost none, negative), a few (some, positive) and the few (the small number there is); the same three-way contrast applies to little, a little and the little. A wrong choice here, such as few water or much friends, is a frequent improvement target.
Error Type 6: Word Order and Redundancy
Two stylistic faults are tested as “improvements” even when no grammar rule is broken: wrong word order and redundancy (saying the same thing twice).
Misplaced modifiers change the meaning: I only ate two mangoes suggests you did nothing else but eat them; the intended I ate only two mangoes limits the number. Place only, even, almost, nearly immediately before the word they modify.
Redundancy appears in pairs that repeat an idea: return back, repeat again, reason because, more preferable, free gift, final conclusion, new innovation. The improved option simply drops the duplicate word — return, repeat, preferable. The same logic flags wordy phrases the examiner trims down: in spite of the fact that becomes although, in the event that becomes if, and at this point in time becomes now. When two options say the same thing but one is shorter and still correct, the shorter version is usually the intended improvement.
Wrong: Please revert back to me.
Right: Please revert to me. — revert already means “come back”, so back is redundant.
The 'No Improvement' Trap
One option, usually the last, is “No improvement” (or “No correction required”). Examiners include sentences that are already correct, precisely so that nervous candidates change a perfectly good sentence and lose the mark. This is the over-correction trap.
Choose “No improvement” with confidence when, after your four-step check, you find the underlined part is grammatical and idiomatic. Do not reject it merely because the sentence “sounds formal” or you would phrase it differently. Style preference is not an error.
An option is the answer only if it fixes a genuine grammatical or idiomatic fault. If every alternative introduces a new error and the original is clean, the correct choice is “No improvement”.
Worked Example: The Method in Action
Let us run the four-step method on a typical question and reach the answer logically rather than by feel.
Improve the underlined part: If I would have known your address, I would have written to you.
(a) had known (b) have known (c) would knew (d) No improvement
The trap option (d) tempts students who never learnt the third-conditional pattern. By naming the structure first — If + past perfect in the if-clause, would have + past participle in the result — you eliminate (b), (c) and (d) instantly. This is why Step 3 (naming the error) is the heart of the method.
Mistakes to Avoid in This Section
Beyond the grammar traps, candidates lose marks to a handful of strategic errors. Guard against each one.
- Reading options first and letting an attractive distractor anchor your judgement.
- Over-correcting a sentence that is already right — respect the “No improvement” option.
- Fixing words outside the underline — only the marked part is in play.
- Choosing the “fancier” word — the test rewards correctness, not vocabulary show.
- Ignoring a second error — sometimes the right option fixes both a preposition and a tense; check the whole segment.
- Trusting your ear over the rule — spoken habits like different than or could of are wrong in formal grammar.
Speed comes from pattern recognition, not from reading faster. Drill the six error types until you can label a sentence’s fault within a few seconds — then the correct option is obvious.
Previous-Year Question and Recap
Q. Improve the underlined part: Hardly had I reached the platform than the train started moving.
(a) when (b) then (c) until (d) No improvement
Answer: (a) when. The correlative of hardly… is when (and of scarcely… is when, while no sooner… pairs with than). So the correct sentence is “Hardly had I reached the platform when the train started moving.” Option (d) is the over-correction trap.
- Use the four steps: read → check subject/verb → name the error → frame your own fix.
- Six recurring errors: tense/sequence, concord, prepositions, comparison, articles, word order/redundancy.
- Learn idioms as fixed phrases: different from, superior to, comprises (no ‘of’).
- Third conditional: If + past perfect… would have + V3.
- Correlatives: hardly/scarcely…when, no sooner…than.
- Respect “No improvement” — never over-correct a clean sentence.
Frequently asked questions
How many sentence-improvement questions come in the CDS English paper?
The improvement-of-sentences block appears every year and usually carries several questions. Because each tests a single objective grammar point, it is one of the most dependable scoring sections if you practise the error types.
Should I read the four options before correcting the sentence?
No. Frame your own correction first, then match it to the closest option. Reading the options first lets an attractive distractor bias your judgement, which is exactly what the examiner intends.
When should I choose the 'No improvement' option?
Choose it only after your four-step check shows the underlined part is already grammatical and idiomatic, and every other option introduces a new error. Do not reject it just because you would phrase the sentence differently; style preference is not a fault.
What is the third conditional pattern tested in these questions?
For an unreal past situation, use 'If + past perfect' in the if-clause and 'would have + past participle' in the result clause, e.g. 'If I had known, I would have come.' Forms like 'If I would have known' are wrong.
Which correlatives are commonly tested in sentence improvement?
Remember the fixed pairs: 'hardly/scarcely ... when', 'no sooner ... than', 'either ... or', 'neither ... nor', and 'not only ... but also'. Mixing these (for example 'hardly ... than') is a classic error the examiner inserts.
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