What is Sentence Completion in IELTS Reading?

You complete a sentence by filling a gap with words taken directly from the passage. A strict word limit is always given — usually 'NO MORE THAN TWO WORDS', 'NO MORE THAN THREE WORDS AND/OR A NUMBER', or 'ONE WORD ONLY'. The answer must be copied exactly as it appears in the text. You cannot paraphrase or change the word form.

What happens if I exceed the word limit?

You score zero for that answer — even if the content is correct. This is one of the most avoidable errors in IELTS Reading. Always read the word limit instruction before you begin answering, and count your words before writing your final answer.

Do Sentence Completion answers follow the order of the passage?

Yes. Unlike Matching Headings, Sentence Completion answers appear in the same order as the passage. Once you find the answer to Question 5, the answer to Question 6 will be somewhere after that point in the text. Use this to scan forward efficiently.

Can I paraphrase the answer in Sentence Completion?

No. You must copy the exact words from the passage. If the passage says 'the temperature declined sharply' and you write 'temperature fell,' that is wrong even though the meaning is the same. The sentence stem is designed so that only the exact passage words fit grammatically and correctly.

Do articles (a, an, the) count toward the word limit?

Yes. 'A rapid decline' is three words, not two. 'The spring equinox' is three words. If your limit is two words, check whether the sentence stem already includes the article. 'The experiment occurred during the ___' already has 'the' — write 'spring equinox' (two words) not 'the spring equinox' (three).

What is the difference between Sentence Completion and Summary Completion?

Sentence Completion gives you individual standalone sentences, each testing a specific fact from a specific part of the passage. Summary Completion gives you a paragraph-length summary with multiple gaps — the gaps relate to a longer section of the passage, and sometimes a word box is provided instead of requiring you to find words in the text.

Reading10 min read·Updated June 5, 2026

IELTS Reading Sentence Completion: Rules for Exact Word Matches

The word-limit rule that loses most marks, how to scan for paraphrased answers, and a step-by-step method for sentence completion with worked examples.

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IELTS Reading sentence completion strategy with word limit table and examples

Written by mockDe Editorial Team· IELTS preparation specialists

Last Updated June 5, 2026

10 min read

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IELTS Reading Practice

Key Takeaways

Copy exact words from the passage. Never paraphrase or change word form.
Read the word limit instruction before you start any question group. Not after.
Exceeding the word limit = zero marks, even if the content is correct.
Answers follow passage order — scan forward from where you found the last answer.
Hyphenated words (long-term, amyloid-beta) count as ONE word.

How do I answer Sentence Completion questions in IELTS Reading?

Find the passage section using keywords from the sentence stem. Copy the exact words that complete the sentence — within the stated word limit. The question uses different vocabulary from the passage (paraphrase), so scan for the meaning, not the exact question words.

Read the word limit first — always, before starting
Underline the key noun or verb in the stem to guide your scan
Scan for paraphrase synonyms — the passage rarely uses the same words as the question
Count your words before writing — articles and prepositions count

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Part of the IELTS Reading cluster

IELTS Reading: The Complete Blueprint

What is Sentence Completion?

You fill a gap in a sentence using words taken directly from the reading passage. A word limit is always stated. You must copy the exact words — never paraphrase.

Exceeding the word limit scores zero even if the content is correct. This is one of the most preventable errors in IELTS Reading.

What Is Sentence Completion?

You get a set of incomplete sentences. Each one relates to a specific part of the passage. Your job is to find the exact words in the passage that fill the gap.

It sounds simple. The difficulty comes from two things. First, the question uses different words from the passage — you cannot just search for the question words. Second, there is a strict word limit that disqualifies even a correct answer if you write too many words.

The good news: answers follow the order of the passage. Once you find one answer, the next one is always further along in the text — never before it.

The Word Limit Rule

Before you answer a single question, read the instruction box at the top of the question group. It will say something like: Complete the sentences. Choose NO MORE THAN TWO WORDS from the passage for each answer.

That limit is not a guideline. It is a rule. Breaking it scores zero. The examiner does not give partial credit. A three-word answer to a two-word question is zero marks.

Instruction	What it means	Valid answers
ONE WORD ONLY	Exactly one word	'rapidly' ✓ — 'rapid decline' ✗
NO MORE THAN TWO WORDS	One or two words	'rapid decline' ✓ — 'a rapid decline' ✗
NO MORE THAN THREE WORDS	One, two, or three words	'a rapid decline' ✓
NO MORE THAN THREE WORDS AND/OR A NUMBER	Up to 3 words plus a number counts as one unit	'less than 5%' ✓

The 6-Step Method

1. Read the word limit first

Before looking at any question. Write the limit in the margin if it helps. Checking it after you have written a three-word answer is too late.

2. Underline the key word in the stem

Find the most specific noun or verb — a number, a name, a technical term. This is your scanning anchor in the passage.

3. Predict the word type

From the grammar of the stem, you can often tell what type of word fills the gap. 'The process takes ___' needs a time expression. 'The material is described as ___' needs a noun or adjective.

4. Scan the passage using synonyms

The question almost never uses the same words as the passage. 'Increased' in the question might be 'rose' or 'grew' in the passage. Scan for the meaning, not the exact words.

5. Read the 2–3 sentences around your target carefully

Once you locate the right area, read carefully. The answer is in these sentences. Verify it fits both grammatically and logically in the stem.

6. Count your words before writing

Count every word — including articles and prepositions. Check whether any word can be cut without losing the meaning. Then write.

The Paraphrase Gap

The question uses different words from the passage. This is intentional. If the question used the same words, you could just search for them. IELTS wants to test whether you understand the idea — not whether you can copy-match text.

These paraphrase pairs are common:

Question word	Likely passage word
increase / grow / rise	surge, expand, escalate, climb, accelerate
decrease / fall / drop	decline, reduce, diminish, contract, shrink
important / significant	critical, vital, key, substantial, major
says / argues	claims, asserts, contends, suggests, proposes
study / research	investigation, analysis, examination, survey
cause / lead to	result in, trigger, give rise to, produce, generate
improve / better	enhance, advance, strengthen, optimise, refine

For a full guide on paraphrase recognition, see our article on spotting synonyms in IELTS Reading.

Word Count Traps: Articles, Numbers, Hyphens

People lose marks here without realising it. Know these rules:

Articles count as words

'a rapid change' = 3 words. 'rapid change' = 2 words. Check whether the sentence stem already provides the article.

Prepositions count as words

'in the morning' = 3 words. 'the morning' = 2 words. Only include a preposition if the stem requires it for grammar.

Hyphenated compounds = 1 word

'long-term', 'well-known', 'cost-effective', 'amyloid-beta' — each counts as ONE word, even though they contain two parts.

Numbers as digits = 1 word

'7.5' is one word. '7.5 million' is two words. 'seven point five' is three words. Use digits when the passage uses them.

Numbers written out = counted normally

'forty-two' is one word (hyphenated). 'forty two' without a hyphen is two words. Follow whatever form appears in the passage.

Practice: 6 Questions With Reveal

Use the passage below to answer all six questions. Complete each sentence using words from the passage. Then reveal the answer to see the correct word(s), where they are in the passage, and what trap was set.

Passage

The science of sleep

Sleep occupies roughly one-third of human life, yet for most of history its purpose remained mysterious. For decades, scientists assumed that sleep was essentially a passive state — a period of reduced activity during which the body simply rested. Modern research has fundamentally overturned this view. Sleep is now understood to be a highly active process, during which the brain performs critical maintenance tasks that are impossible to carry out during wakefulness.

Chief among these tasks is memory consolidation. During slow-wave sleep, the brain replays the neural patterns associated with experiences from the preceding day, effectively transferring information from short-term to long-term memory. Studies using brain scanning technology have confirmed that this process can enhance learning outcomes by up to 40 percent. Disrupting slow-wave sleep, even briefly, measurably impairs the ability to recall recently learned material.

A second function of sleep involves the removal of metabolic waste from the brain. The glymphatic system — a network of channels surrounding blood vessels — becomes significantly more active during sleep, flushing out potentially harmful proteins including amyloid-beta, which accumulates in the brains of Alzheimer's patients. Some researchers now argue that chronic sleep deprivation may be a contributing factor in the development of neurodegenerative conditions, though this relationship has not yet been definitively established.

The consequences of insufficient sleep extend well beyond cognitive function. A single night of less than six hours of sleep reduces natural killer cell activity by 70 percent, temporarily weakening the immune system. Sustained sleep restriction over several weeks has been linked to elevated blood pressure, increased inflammation markers, and impaired regulation of blood glucose — all recognised risk factors for cardiovascular disease.

Q1.ONE WORD ONLY

"For most of human history, sleep was believed to be a ___ state during which the body rested."

Q2.NO MORE THAN TWO WORDS

"During slow-wave sleep, the brain replays neural patterns and transfers information from short-term to ___ memory."

Q3.NO MORE THAN TWO WORDS

"Brain scanning studies show that slow-wave sleep can improve ___ by up to 40 percent."

Q4.NO MORE THAN TWO WORDS

"The glymphatic system becomes more active during sleep, removing harmful substances including ___ from the brain."

Q5.NO MORE THAN TWO WORDS

"Scientists have suggested that regular ___ may contribute to neurodegenerative diseases, but this has not been conclusively proven."

Q6.NO MORE THAN THREE WORDS

"Even one night of fewer than six hours of sleep can reduce the effectiveness of the ___ by 70 percent."

Word limits are won in practice

Take a full timed reading test and enforce the word count rule strictly on every sentence completion answer. Track how many marks you save compared to unchecked answers.

Take a Reading Practice Test