In IELTS Reading sentence completion you get a list of sentences about the passage, each with a gap. You fill each gap with words from the text, so the completed sentence says what the passage says. The official description sets the rules:
- You choose words from the text and type them into the gap.
- The instruction gives a word limit, for example NO MORE THAN TWO WORDS AND/OR A NUMBER. Writing more than the limit loses the mark.
- Hyphenated words such as check-in count as one word, and contracted words such as they're are not tested.
- In Academic Reading, the questions are in the same order as the information in the text.
The General Training page groups sentences with summary, note and table completion, and says those answers may not come in order, although they usually come from one part of the text (ielts.org).
Don't confuse this task with matching sentence endings, where you choose an ending from a list. In sentence completion there is no list: you copy words or a number from the passage, within the stated limit.
Where sentence completion marks are lost
Sentence completion is one of the harder Reading tasks in GoPrep mocks. 55% of sentence completion answers scored 0, against 50% across all Reading question types in the same mocks (270,000 answers). Only matching sentence endings (62%) and matching headings (60%) were higher (13,552 sentence completion answers in full GoPrep Reading mocks, 12 September to 11 October 2026).
A large part of that is empty gaps: 27% of all sentence completion answers were left blank, so almost half of the lost marks (3,604 of 7,459) were blanks. Here is how it changes with the level:
| Band of the mock | Answers that scored 0 | Answers left blank | Blanks among answers that scored 0 |
|---|---|---|---|
| Below 5.0 | 85% | 57% | 67% |
| 5.0-5.5 | 59% | 18% | 30% |
| 6.0-6.5 | 37% | 8% | 22% |
| 7.0-7.5 | 20% | 3% | 16% |
| 8.0 and above | 8% | 1% | 14 of 78 |
Below band 5, two out of three lost marks are empty gaps. From band 6 up, most lost marks are words that were written but wrong.
We also compared every wrong answer that was not blank with the answer key (3,855 answers in the same period). About 1 in 5 (729) overlapped with or closely resembled an accepted answer. The comparison was automatic, so treat the split as approximate:
| What went wrong | Share of wrong answers | Example: key card catalogue |
|---|---|---|
| The right words plus extra words | 6% (213) | old card catalogue |
| Only part of the answer | 8% (316) | catalogue |
| A spelling slip | 4% (138) | card catalouge |
| A different -s or -es ending | 2% (62) | card catalogues |
| None of the above: a different word or phrase | 81% (3,126) | wooden drawers |
So about a fifth of the non-blank mistakes were close to the key: too many words, too few, an ending or a few letters off. In 159 of the 213 answers with extra words, it was a single extra word. A final check against the limit and the text catches this kind of mistake. The other 81% were a different word or phrase. The comparison doesn't show why, so the method below covers both finding the right place and copying from it exactly.
How to answer sentence completion in 5 steps
- Read the instruction. Note the word limit and whether the words must come from the passage. ONE WORD ONLY, NO MORE THAN TWO WORDS and NO MORE THAN THREE WORDS AND/OR A NUMBER are all used (IDP).
- Predict the gap. Read the whole sentence and decide what is missing: a noun, a verb, an adjective or a number? Singular or plural? The grammar around the gap tells you (see the table below).
- Find the lines. Pick an anchor from the sentence: a name, a number or a term the passage will probably keep. In Academic Reading, scan forward from your last answer. In General Training, use the order as a guide but don't rule out other lines in the same part of the text. The sentence in the question is usually a paraphrase (the same idea in other words), so look for the idea, not the exact words.
- Copy only the words you need. Take the words that complete the meaning, nothing more. Copy the spelling and the form exactly as printed. Numbers can be written as figures or words, within the limit.
- Read the finished sentence back. Check four things: it is grammatical, it says what the passage says, it is inside the limit, and every letter matches the text.
The grammar of the gap
The words around the gap are a free clue. IELTS says that for gap-fill tasks you need to think about the type of word that will fit, for example a noun or a verb. Before you look at the passage, check what comes just before and just after the gap. These are typical clues, not fixed rules, so always read the whole sentence:
| Before or after the gap | You need | Example |
|---|---|---|
| a / an ___ (no noun after the gap) | a singular noun or noun phrase | stored in a ___ → card catalogue |
| many / several / two ___ | a plural noun | several ___ were lost → maps |
| can / will / must ___ | the base form of a verb | farmers can ___ the soil → protect |
| was / were / has been ___ (by) | usually a past participle | were ___ by gardeners → donated |
| very ___, more ___ than | an adjective or an adverb, depending on the sentence | more ___ than before → reliable; moves very ___ → slowly |
| ___ percent, in ___ (a year) | a number | rose by ___ percent → 40 |
This check also protects you from your own mistakes. You are not allowed to change the word you copy: if the passage says dehydration and the gap needs dehydrated, you have found the wrong word, so keep looking. In our data, 62 wrong answers differed from the key only by an -s or -es ending, the kind of slip that reading the sentence back catches.
The word limit works the same way. Every word you type counts, including the, a and of. If the key is card catalogue and the limit is two words, the card catalogue is three words and scores 0. Most of the time the article is already in the sentence before the gap, so you don't need it.
Practice: 5 sentences, one passage
We wrote this passage for the guide; the town of Lorvik is invented. Give yourself 6 minutes and write your answers down before you read the key.
The seed library
When the public library in Lorvik began lending seeds in 2018, staff kept them in an old card catalogue, the wooden drawers once used for book records. Borrowers take a packet of seeds in spring, grow the plants, and return a small share of the new seeds in autumn. Nobody pays a fine if a harvest fails; the librarians simply ask for a short note explaining what went wrong.
The scheme began with 40 varieties, mostly beans and tomatoes. It now offers more than 300, and about a quarter of them were donated by local gardeners rather than bought. The most requested is a purple bean that one family has grown in the area for over a century.
Not every plant suits the scheme. Squash, for example, cross-pollinates easily, so the seeds a borrower returns may produce something quite different from the original plant.
Questions 1–5. Complete the sentences below. Choose NO MORE THAN TWO WORDS AND/OR A NUMBER from the passage for each answer.
- At first, the library stored its seeds in a ___ .
- Borrowers whose harvest fails are asked to write a ___ .
- When the scheme started, it offered ___ varieties.
- Around a quarter of the varieties were ___ by people from the area.
- Seeds from squash may not grow true to the original because the plant ___ easily.
| Question | Answer and proof | Why the tempting answer fails |
|---|---|---|
| 1 | card catalogue: kept them in an old card catalogue | old card catalogue is three words, over the limit. wooden drawers is plural, so it can't follow a |
| 2 | short note or note: ask for a short note | fine is a word match: the passage says nobody pays one |
| 3 | 40: began with 40 varieties | The passage says there are more than 300 varieties now; the question asks about the start. started = began |
| 4 | donated: donated by local gardeners | bought also fits the grammar, but the passage says donated … rather than bought. donate is the wrong form |
| 5 | cross-pollinates: one hyphenated word | cross-pollinate breaks the grammar after the plant. Writing it without the hyphen risks a spelling error |
Question 4 shows what grammar can and can't do. The sentence is a paraphrase: around a quarter = about a quarter, people from the area = local gardeners. The gap sits between were and by, so you need a past participle, and the passage has two: donated and bought. Grammar narrows the choice; meaning decides it. The varieties came from local gardeners, so the answer is donated.
FAQ
What is sentence completion in IELTS Reading?
It is a Reading task where you complete sentences about the passage by filling each gap with words taken from the text. The instruction sets a word limit, and an answer over the limit loses the mark.
Are sentence completion answers in order?
In Academic Reading, IELTS states that sentence completion questions are in the same order as the information in the text. On the General Training page sentences are grouped with summary and note completion, where answers may not come in order but usually come from one part of the text.
Do articles like the and a count towards the word limit?
Yes. Every word you write counts. The article is usually already in the sentence before the gap, so you rarely need to add it.
Does a hyphenated word count as one word in IELTS?
Yes. IELTS states that hyphenated words such as check-in count as single words.
Can my answer have two words and a number?
Yes, if the instruction says NO MORE THAN TWO WORDS AND/OR A NUMBER: you may write up to two words, a number, or both. The words still have to come from the passage.
What do brackets mean in an answer key?
In practice answer keys, a word in brackets, such as (short) note, is optional: the answer is correct with or without it. You never type the brackets themselves.
Can I change the form of a word to fit the gap?
No. The answer must be taken from the passage as it is written. If the word you found doesn't fit the grammar of the gap, look for a different word.
Does spelling matter in IELTS Reading?
Yes. IELTS warns that you will lose marks for incorrect spelling and grammar, so copy each word letter for letter from the passage.
What is the difference between sentence completion and summary completion?
Sentence completion gives separate sentences with one gap each. Summary completion gives a paragraph with several gaps, sometimes with a box of words to choose from, and its answers may not follow the order of the text.
What to practise next
Sentence completion trains two habits: predicting the word from the grammar and copying it exactly. The same habits decide summary completion, where a whole paragraph has gaps, and short-answer questions, where there is no sentence frame at all. In Listening, the gap-fill rules are similar, but you take the words from what you hear: see IELTS Listening form completion. For every Reading task in one place, see the IELTS Reading question types.
The next step is a plan. Tell the quiz your target score, your exam date and the part of IELTS you find hardest, and GoPrep will build a personal study plan around your answers.
P.S. The full Completion lesson and further practice are in the GoPrep course.
GoPrep Team
GoPrep guide authors
We write about IELTS preparation using platform data and official exam materials.
All articles by GoPrep Team