IELTS Reading sentence completion: grammar tells you the answer's shape

Sentence completion is the Reading task where preparation converts most directly into marks, because half the work can be done before reading the passage: the incomplete sentence's grammar dictates what can possibly fill it. "The larvae feed mainly on ____" needs a noun phrase; "Researchers were surprised that the samples ____ within days" needs a past-tense verb phrase; an article before the gap ("a ____") promises a singular noun starting with a consonant sound. Candidates who scan with the answer's shape already in mind find it in seconds; candidates who scan for topic words alone read the same paragraph three times. The same grammar-first instinct is the backbone of summary completion, in both its versions.

The rules the task is built on

• Answers are lifted verbatim. Unlike summary completion with a word list, sentence completion answers come exactly as printed in the passage — no changing word forms, no synonyms of your own. If your candidate answer needs the passage's noun pluralised to fit, it's the wrong candidate; the test always arranges the frame so a literal lift is grammatical.
• The word limit is absolute. NO MORE THAN TWO WORDS AND/OR A NUMBER means a three-word answer scores zero even when semantically perfect. The limit is also a hint: a ONE WORD limit tells you the target is a single strong noun, so stop hunting phrases. Hyphenated compounds count as one word; "a" and "the" count as words — and are almost never needed.
• Questions follow passage order. The answer to question 32 sits after 31's and before 33's — so a found neighbour brackets the search zone. This is the order advantage: do the easy items first because their locations fence in the hard ones, then hunt the stragglers inside known bounds.
• The stem paraphrases the passage. The frame sentence around the gap will not use the passage's wording — "feed mainly on" may appear as "their principal diet consists of". Mark the stem's content words and generate disguises before scanning, exactly as for matching tasks; the gap's answer is verbatim, but the road to it never is.

A worked routine

1. Read the stem; say to yourself what part of speech and number the gap needs, and note the limit.
2. Underline the stem's anchors — names, numbers, technical terms survive paraphrase best.
3. Scan the current search zone (bracketed by neighbours already found) for the anchors' territory; read that sentence and its neighbours precisely.
4. Lift the answer exactly, count its words against the limit, and read the completed sentence back: it must be grammatical and mean what the passage means. A grammatical sentence saying something the passage doesn't is the task's favourite near-miss.