Use of English — Part 4
Key Word Transformations
The highest-stakes part of the B2 First paper — and the one where candidates consistently leave the most marks behind. Every question hides two transformations. Learn to spot both.
If you understand B2 grammar but keep writing 6 words when the limit is 5, or you know the structure but lose the second mark because you miss the secondary transformation — this guide targets those exact failure points. It's also for candidates who avoid Part 4 in practice and hope to compensate elsewhere. Don't. With 12 marks at stake (2 per question), Part 4 is the single highest-value target for score improvement in the entire Use of English paper.
What exactly is Part 4?
You are given a complete sentence and a key word in capitals. Below is a second sentence with a gap. You must complete the second sentence so that it means the same as the first, using the key word. The key word cannot be changed in any way — not its tense, not its form, not anything. The completed gap must contain between 2 and 5 words, including the key word.
She started working here three years ago.
WORKING
She has _______________________________ three years.
Answer: been working here for (4 words, key word included)
The double-transformation rule
This is the single most important insight about Part 4 that most guides skip: every question tests two changes simultaneously. The key word forces one change. A secondary transformation — grammatical or lexical — is always embedded alongside it. Students who only make one change typically score 1/2, not 2/2.
"They repaired the bridge last month." → KEY WORD: REPAIRED
Student who makes ONE change: "The bridge was repaired by them last month." ← 1/2
Correct: "The bridge was repaired last month." ← 2/2
Two changes: passive voice + removal of unnecessary agent "by them"
The 6 transformation types that account for the majority of Part 4 questions at B2:
5 strategies for Part 4
Read the key word first — it tells you the structure
The key word is never random. Cambridge chooses it because it forces a specific grammatical construction. Before reading the full sentences, look at the key word and ask: "What structure does this word belong to?" MADE → causative or past simple? BEEN → passive or present perfect? SINCE → present perfect with time marker. This 5-second classification narrows your transformation approach before you've even read the sentences.
Hunt for both transformations before writing
Once you've identified the primary transformation (the one the key word forces), actively look for the secondary one. Compare the first and second sentences carefully: what else changes between them? A time expression? A pronoun? A negation? The agent in a passive? Writing your answer before identifying both changes is the most expensive mistake in Part 4.
Count words — every time, without exception
2–5 words including the key word. Contractions count as two (can't = can + not = 2 words). This rule is absolute: 6+ words = 0 marks regardless of grammatical accuracy. After writing your answer, count with your finger. Candidates who skip this step lose marks they correctly earned on the grammar.
Verify meaning equivalence — not just grammatical correctness
Your transformed sentence must mean exactly the same as the original. A grammatically perfect sentence that shifts the meaning earns 0. After writing your answer, read both sentences together and ask: "Does this mean the same thing?" Pay particular attention to negation (not reversing it), time reference (present vs past), and degree (comparative values preserved).
Always write something — even if uncertain
Partial marking means a half-right answer earns 1 mark. If you're unsure of the complete transformation, write what you know: include the key word in a grammatical context, complete the second sentence meaningfully, and you have a real chance of earning partial credit. Leaving it blank guarantees 0. A reasonable attempt at 5/6 questions beats a perfect 4/6 in nearly every scenario.
3 mistakes that cost candidates marks
The single most costly error in Part 4 — and one that cannot be recovered through partial marking. Students under time pressure change verb tenses, add prefixes, or use a related form. "MAKE" becomes "made" or "making" or "makes". The instruction is unambiguous: the key word must appear exactly as printed. Build in a final check specifically for this.
The upper limit of 5 words is the most frequently violated rule in Part 4. Students who write a grammatically correct 6-word answer earn 0. This happens most often on modal perfect questions ("must not have been told") where candidates include an unnecessary "been" or article. Count every time.
Missing the secondary transformation is the difference between 1/2 and 2/2 on every question. Cambridge specifically designs questions so that the "obvious" transformation — the one the key word makes unmistakeable — only earns partial credit. The second mark requires noticing what else changes: a time expression, a negation, an agent removed from a passive, a preposition changed by a reporting verb.
6 annotated examples
Each example identifies both transformations — primary and secondary.
"It is possible that she left before we arrived."
She ___ before we arrived.
>_ Answer: "might have left"
Primary: modal perfect (possible past event)
Secondary: tense shift (present → past possibility)
"A mechanic repaired our car at the garage."
We ___ at the garage.
>_ Answer: "had our car repaired"
Primary: causative have (have + object + past participle)
Secondary: agent removed (mechanic disappears from the sentence)
"She last spoke to her mother on Tuesday."
She ___ her mother since Tuesday.
>_ Answer: "hasn't spoken to"
Primary: present perfect + since (hasn't + past participle)
Secondary: affirmative → negative (last spoke → hasn't spoken)
"No other student in the class works as hard as Maria."
Maria ___.
>_ Answer: "is the hardest-working student in the class"
Primary: superlative (hardest-working)
Secondary: verb → adjective nominalization (works hard → hardest-working)
"'Don't touch the exhibits,' the guard told us."
The guard ___.
>_ Answer: "warned us not to touch the exhibits"
Primary: reporting verb + infinitive (warn sb not to do)
Secondary: direct → indirect speech (imperative → infinitive)
"You won't get a refund if you don't have a receipt."
You won't get a refund ___.
>_ Answer: "unless you have a receipt"
Primary: conditional connector (unless = if not)
Secondary: double negative removed (don't have → have, with negation carried by "unless")
Practice quiz — choose the correct transformation
Select the correctly completed second sentence. One option has too many words, one changes the key word, and one makes only the primary transformation. Find the answer that nails both.
Original: "It is possible that she left before we arrived." Key word: MIGHT She ___ before we arrived.
Original: "A mechanic fixed our car at the garage last week." Key word: HAD We ___ at the garage last week.
Original: "She last spoke to her mother on Tuesday." Key word: SPOKEN She ___ her mother since Tuesday.
Original: "No other student in the class works as hard as Maria." Key word: HARDEST Maria ___.
Original: "'Don't touch the exhibits,' the guard told us." Key word: WARNED The guard ___.
Frequently asked questions
How many words can I write in a B2 First Key Word Transformation? >
Can I change the key word? >
Is partial marking possible in B2 Part 4? >
What are the most common structures in B2 Part 4? >
Is B2 Part 4 the same as C1 Part 4? >
How Part 4 compares to the other Use of English parts
| Part | Format | Marks | Per Q | Difficulty |
|---|---|---|---|---|
| Part 1 · Multiple Choice Cloze | 8 gaps · choose A/B/C/D | 8 | 1 mark | ★★★☆☆ |
| Part 2 · Open Cloze | 8 gaps · no options | 8 | 1 mark | ★★★★☆ |
| Part 3 · Word Formation | 8 gaps · root word given | 8 | 1 mark | ★★★☆☆ |
| Part 4 · Key Word Transformations | 6 sentences · key word | 12 | 2 marks | ★★★★★ |
Part 4 is the only part with 2 marks per question — and the only part where partial credit is available. This makes it both the highest-risk and the highest-reward part of the Use of English paper.
Practice Part 4 in full exam conditions
The free demo at /b2 is a Part 1 Multiple Choice Cloze exercise. The 5 full B2 First exams in the complete pack include all 7 parts of the exam — including Part 4 Key Word Transformations with full answer keys and transformation-by-transformation explanations.