In Sentence Improvement, the NDA gives you a sentence with one part underlined and asks you to pick the option that makes it grammatically correct. If nothing is wrong, you choose ‘No improvement’. It is pure applied grammar — no vocabulary cramming needed. This guide from The Cavalier shows you the exact rules examiners test and how to attack each question.
What Sentence Improvement Really Tests
A Sentence Improvement question gives you a complete sentence with one segment underlined. Four options follow — three are possible replacements for that underlined part and one is usually ‘No improvement’. Your task is to choose the option that makes the sentence grammatically correct and naturally worded.
Unlike Spotting Errors, where you only locate the mistake, here you must also fix it correctly. So you need to know not just that something is wrong, but what the right form is. This is why the topic rewards students who understand rules rather than those who rely on a ‘feel’ for English.
Only the underlined part can change. The rest of the sentence is fixed and correct. Never pick an option that fixes the underlined part but clashes with the unchanged words around it.
The good news: the same grammar rules — tenses, subject-verb agreement, prepositions, articles, and modifiers — appear year after year. Master a short list of rules and you can crack most questions even under time pressure.
Why This Topic Is Worth Your Time
The NDA English paper carries 200 marks (100 questions of 2 marks each). Grammar-based question types — Spotting Errors, Sentence Improvement and Sentence Completion — together form a large, reliable block. Sentence Improvement is among the most scoring because the answer is decided by fixed rules, not opinion.
- It needs no vocabulary memorisation — only grammar.
- Rules repeat, so practice transfers directly to the exam.
- Once you know the rule, the answer is objective and certain.
NDA has negative marking: roughly 0.83 marks (one-third of 2.5) is cut for a wrong answer. In Sentence Improvement, if you cannot name a clear error, ‘No improvement’ is often safer than a random guess.
Students who revise grammar little and often build a huge edge here. A page of rules a week, applied to past papers, beats last-minute cramming.
A Reliable Step-by-Step Method
Do not just read the four options and pick whatever ‘sounds nice’. Follow a fixed routine so you never miss the rule being tested.
- Read the full sentence once for meaning, ignoring the underline.
- Focus on the underlined part and ask: is there a tense, agreement, preposition, article or word-order issue?
- Check the surrounding words — the time words, the subject and the verb — because they decide what the underlined part must be.
- Test each option by mentally inserting it back into the full sentence.
- If every option introduces a new error, choose ‘No improvement’.
The right option must agree with the unchangeable rest of the sentence. Always re-read the whole sentence with your chosen option in place before finalising.
This discipline prevents the most common trap: picking an option that is grammatically pretty on its own but does not fit the fixed parts of the sentence.
Rule 1: Tense and Time Markers
Tense errors are the most tested. The trick is to let the time words in the sentence decide the correct tense of the underlined verb.
- since / for with an ongoing action → present perfect or present perfect continuous: He has lived here since 2010.
- ago / yesterday / last year → simple past: She left an hour ago.
- Two past actions, one before the other → the earlier one takes past perfect: The train had left before we reached.
- After if (real condition), use present + will: If it rains, we will stay.
So if a sentence reads ‘He is working here since 2015’, the time marker since demands has been working. The underlined ‘is working’ is wrong and the improvement is ‘has been working’. Always let the time signal, not your ear, choose the tense.
Using simple present with since/for. ‘I know him for five years’ is wrong; it must be ‘I have known him for five years.’
Rule 2: Subject-Verb Agreement
The verb must agree with its real subject in number, even when other words sit between them. Examiners love to hide the subject behind a phrase to confuse you.
- Singular subject → singular verb; plural subject → plural verb.
- Each, every, everyone, anybody, nobody, neither, either → singular verb.
- Two subjects joined by and → usually plural; joined by or / nor → verb agrees with the nearer subject.
- Collective nouns (team, jury, family) usually take a singular verb when acting as one unit.
In ‘The quality of these mangoes are poor’, the subject is quality (singular), not mangoes. The improvement is is poor. Strip away the in-between phrase ‘of these mangoes’ and the agreement becomes obvious.
Letting a noun nearest to the verb control it. In ‘Neither the teacher nor the students was present’, the verb follows the nearer subject students, so it should be were.
Rule 3: Correct Prepositions
Many words pair with a fixed preposition. Using the wrong one is a favourite test. There is no shortcut except learning the common pairs.
- good at, bad at (a skill) — good at maths
- angry with a person, angry at a thing
- different from, not ‘different than’
- married to, not ‘married with’
- composed of, capable of, afraid of
- superior to / inferior to, never ‘than’
So in ‘She is married with a doctor’, the underlined preposition is wrong; the improvement is married to a doctor. Likewise, ‘He is senior than me’ should be senior to me.
When the underlined part is just a short preposition, the question is almost certainly testing a fixed word-preposition pair. Recall the standard partner of the verb or adjective next to it.
Rule 4: Articles and Determiners
Articles (a, an, the) are small but heavily tested. The choice depends on sound and on whether the noun is specific.
- Use a before a consonant sound, an before a vowel sound: a university (you-sound), an hour (silent h), an MLA (em-sound).
- Use the for something specific or unique: the Sun, the Ganga, the Himalayas.
- No article before most uncountable or general plural nouns: Honesty is the best policy.
So in ‘He waited for a hour’, the improvement is an hour, because hour begins with a vowel sound. And ‘She is a honest girl’ should become an honest girl for the same reason.
Choosing the article by spelling instead of sound. ‘An university’ is wrong because university starts with a you sound, so it takes a.
Rule 5: Modifiers, Word Order and Parallelism
Some questions test how words are arranged rather than which word is used. Watch for misplaced modifiers and broken parallel structure.
Misplaced modifiers
A describing phrase should sit next to the word it describes. ‘Walking down the road, the trees looked lovely’ wrongly suggests the trees were walking. The improvement makes the person walk: Walking down the road, I found the trees lovely.
Parallelism
Items in a list must share the same grammatical form. ‘She likes reading, painting and to swim’ mixes forms; the improvement is and swimming so all three are -ing words.
Comparisons must be logical and complete: ‘The climate of Pune is better than Mumbai’ should be than that of Mumbai — you compare climate with climate, not climate with a city.
Degrees of comparison
Do not double a comparative. ‘more better’ is wrong; the improvement is simply better. Similarly, use comparative for two things and superlative for more than two.
Worked Example
Let us apply the full method to a typical question so you can see the thinking in action.
Choose the option that improves the underlined part: ‘He has gone to Delhi yesterday.’ Options: (a) had gone (b) went (c) goes (d) No improvement.
Notice that the time marker yesterday, not your ear, decided the answer. This is the habit that turns guesswork into reliable marks.
Previous-Year Style Question
Here is a question in the exact style NDA uses, with the reasoning spelled out so you can copy the approach.
Q. Improve the underlined part: ‘The number of students in the class are increasing.’ (a) is (b) were (c) have been (d) No improvement
Answer: (a) is. The real subject is ‘the number’, which is singular, so the verb must be is. The phrase ‘of students’ is a distractor. (Note: ‘a number of students’ would take a plural verb, but ‘the number of’ is always singular.)
Mark the subject and the verb with your eyes first. Half of all Sentence Improvement errors are tense or subject-verb agreement, and both become easy once you isolate who is doing the action.
Common Traps to Avoid
Even strong students lose marks to a few recurring traps. Knowing them in advance protects your score.
- Changing more than the underline: only the underlined words can be replaced; never ‘mentally fix’ the rest of the sentence.
- Ignoring ‘No improvement’: sometimes the sentence is already correct. If you cannot name a precise error, this option may be the answer.
- Picking the fanciest option: a longer or more formal phrase is not automatically right. Grammar correctness wins, not style.
- Forgetting context: an option can be perfect in isolation yet clash with the fixed words. Always re-read the whole sentence with the option inserted.
Treating ‘No improvement’ as a trap to be avoided. It is a genuine answer in a fair share of questions; reject it only after you have actively checked for tense, agreement, preposition, article and word-order errors.
Quick Revision and Final Plan
Bring everything together with a tight revision routine. Practise five to ten sentences daily from past papers, naming the rule behind each answer aloud — this builds instant recognition in the exam.
- Read the whole sentence; focus only on the underlined part.
- Let time words fix the tense; let the real subject fix the verb.
- Learn fixed preposition pairs and the a/an/the sound rule.
- Watch for misplaced modifiers, broken parallelism and illogical comparisons.
- Re-insert your option and re-read; if nothing is wrong, pick No improvement.
Treat each wrong answer in practice as a lesson: write down the rule you missed. Over a few weeks your error list shrinks, and Sentence Improvement becomes one of the fastest, most certain sources of marks in your NDA English paper.
Frequently asked questions
What is the difference between Spotting Errors and Sentence Improvement?
In Spotting Errors you only identify which part of a sentence is wrong. In Sentence Improvement you must also choose the correct replacement for the underlined part, so it tests both error-detection and the right grammar form.
When should I choose the 'No improvement' option?
Choose it only after actively checking for tense, subject-verb agreement, preposition, article and word-order errors and finding none. If the underlined part is already correct and every other option introduces a mistake, 'No improvement' is the right answer.
Which grammar rules are most important for NDA Sentence Improvement?
Tenses with time markers, subject-verb agreement, fixed prepositions, articles (a/an/the), and modifiers/parallelism cover the large majority of questions. Mastering these five areas gives you reliable marks.
Does Sentence Improvement need a strong vocabulary?
Not really. It is mainly applied grammar, so you can score well even with average vocabulary as long as you know the rules. This makes it one of the most dependable scoring topics in NDA English.
How do I avoid negative marking in this section?
Eliminate options that break a clear grammar rule, then choose from what remains. If you cannot justify any change with a definite rule, 'No improvement' is usually safer than a random guess given the one-third negative marking.
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