Key Word Transformation is where strong B2 students suddenly lose easy marks. It matters because Part 4 gives you fixed points for grammar control, and Cambridge repeats the same traps: passives, reported speech, inversion, and conditionals.
This part is not really about vocabulary. It is about seeing the grammar pattern fast and rebuilding the sentence without changing the meaning. That is hard because Spanish often pushes you toward a structure that sounds logical but breaks the exam rule. If you know the trigger, the transformation becomes mechanical. If you do not, two missing words can cost you the whole item.
Why key word transformation trips up Spanish speakers
The problem is not just grammar. It is grammar under pressure.
In Part 4, you have an original sentence, a key word that you cannot change, and a gap of two to five words. So you are not writing freely. You are rebuilding meaning inside a tight frame. That is exactly where Spanish habits interfere.
One big false pattern is this: in Spanish, you often keep the same basic structure and just swap a few words. In English, Cambridge often wants a full structural change. Active becomes passive. Direct speech becomes reported speech. Normal word order becomes inversion. A future idea becomes a zero conditional if the meaning is a general truth.
Another problem: Spanish does not force some contrasts as strictly as English exam tasks do. You may understand the meaning perfectly and still choose the wrong grammar because the distinction feels small. Cambridge loves that.
In Spanish: “Dicen que el inglés se habla en todo el mundo” → same idea can stay vague about the subject
In English: “English is spoken all over the world” ✓ / “People speak English all over the world” ✓
Common error: “English speaks all over the world” ✗ — trying to keep the noun as subject without using the passive
That error is very common in transformations. You see a noun like “English” or “the report” and keep it as the subject, but the verb needs a passive form: is spoken, was written, has been sent.
Another false pattern comes with reported speech.
In Spanish: “Ella dijo: ‘Estoy cansada’” → often no big visible tense shift in everyday use
In English: “She said she was tired” ✓ / “She says she is tired” ✓
Common error: “She said she is tired” ✗ — keeping the original tense after a past reporting verb
Spanish speakers also get trapped by word order. In Spanish, emphasis usually comes from intonation or word choice. In English exam grammar, fronted negative adverbials force inversion.
In Spanish: “Nunca había visto algo así” → normal order after “nunca”
In English: “Never had I seen anything like it” ✓ / “I had never seen anything like it” ✓
Common error: “Never I had seen anything like it” ✗ — fronting the adverbial but forgetting inversion
And then there is the conditional trap.
In Spanish: “Si calientas agua a 100 grados, hierve” → present + present
In English: “If you heat water to 100C, it boils” ✓ / “When you heat water to 100C, it boils” ✓
Common error: “If you heat water to 100C, it will boil” ✗ — using will for a general truth
So the real skill in Part 4 is not “knowing English”. It is recognizing which grammar machine Cambridge wants you to switch on.
Core explanation
The four transformation types Cambridge loves
Some Part 4 questions are lexical, but many are structural. The most frequent high-value patterns at this level are passive voice, reported speech, inversion, and zero conditional.
These are good exam targets because they test control, not memorization. You must preserve meaning, use the key word exactly, and respect grammar form.
Here is the core idea:
| Transformation type | What changes | What stays the same |
|---|---|---|
| Passive voice | Focus moves from doer to action/result | Basic event meaning |
| Reported speech | Direct words become reported statement | Message content |
| Inversion | Word order changes after negative adverbial | Main meaning, stronger emphasis |
| Zero conditional | General truth uses present + present | Cause and result |
If you train yourself to spot the trigger, you stop guessing.
Passive voice: rebuild the sentence, not just the verb
Use the passive voice when the object of the active sentence becomes the subject. The form is be + past participle.
Structure:
- Active: subject + verb + object
- Passive: object + be + past participle (+ by + agent)
This is where Spanish speakers often make two mistakes. First, they forget to change be to the right tense. Second, they use the wrong past participle.
Example:
- Active: The team wrote the report.
- Passive: The report was written by the team.
✓ The house was built in 1990.
✗ The house built in 1990.
Why wrong? Because the passive needs be in the correct tense: was built.
✓ English is spoken all over the world.
✗ English is speaked all over the world.
Why wrong? Because the past participle of speak is spoken, not speaked.
In transformations, you often get a sentence like:
- Active: Someone stole my bike yesterday.
- Key word: STOLEN
You need: My bike was stolen yesterday.
Notice the logic:
- active object: my bike → passive subject
- active tense: stole → passive past simple: was stolen
A fast tense map helps:
| Active tense | Passive form | Example |
|---|---|---|
| Present simple | am/is/are + V3 | The rooms are cleaned daily. |
| Past simple | was/were + V3 | The email was sent yesterday. |
| Present perfect | has/have been + V3 | The work has been finished. |
| Future | will be + V3 | The results will be announced tomorrow. |
| Present continuous | am/is/are being + V3 | The road is being repaired. |
✓ The results will be announced tomorrow.
✗ The results will announced tomorrow.
✓ The road is being repaired this week.
✗ The road is repaired this week.
That second wrong example is subtle. Is repaired sounds possible, but it means a general state, not an action in progress. Cambridge uses context words like now, this week, at the moment to force the correct tense.
Reported speech: backshift, pronouns, and deictics
With reported speech, a statement is repeated later, usually after a past reporting verb like said or told. In exam tasks, this usually means backshift.
Structure:
- Direct: “I am tired.”
- Reported: She said (that) she was tired.
The basic shifts:
- present simple → past simple
- present continuous → past continuous
- past simple → past perfect
- will → would
You also often change:
- today → that day
- tomorrow → the next day
- here → there
- this → that
And one rule matters a lot in Part 4:
- say + (that) clause
- tell + object + (that) clause
✓ She said that she was tired.
✗ She said that she is tired.
Why wrong? Because said is past, so the present usually backshifts to past.
✓ He told me that he would call the next day.
✗ He told that he will call tomorrow.
Why wrong? Two reasons: told needs an object, and will / tomorrow should normally become would / the next day.
A common transformation type is:
- Direct: “I will finish it tomorrow,” Ben said.
- Key word: WOULD
Possible answer: Ben said that he would finish it the next day.
Another:
- Direct: “I am not hungry,” she said to me.
- Key word: TOLD
Answer: She told me that she was not hungry.
Students often lose marks because they only do one change. They backshift the verb but forget the pronoun. Or they change tell correctly but keep tomorrow. Cambridge often builds the item so you need all the changes together.
Inversion and zero conditional: formal word order vs general truth
These two patterns are different, but they get mixed up because both feel unnatural at first.
Inversion happens after a negative or restrictive adverbial at the beginning of the sentence: never, rarely, hardly, seldom, not only, little, only then. The order becomes auxiliary + subject.
Structure:
- Normal: I had never seen such a mess.
- Inverted: Never had I seen such a mess.
If there is no auxiliary in the original sentence, you add do/does/did.
✓ Rarely do I see him these days.
✗ Rarely I see him these days.
✓ Never did I understand the reason.
✗ Never I understood the reason.
A very common exam pattern is with hardly:
- Hardly had I arrived when the phone rang.
✓ Hardly had I arrived when the phone rang.
✗ Hardly I had arrived than the phone rang.
Two traps there: inversion after hardly, and when, not than.
Now compare that with the zero conditional. This is not about emphasis. It is about facts that are always true.
Structure:
- If/When + present simple, present simple
Use it for scientific facts, instructions, or routines with automatic results.
✓ If you heat ice, it melts.
✗ If you heat ice, it will melt.
✓ When you press this button, the door opens.
✗ When you press this button, the door will open.
Why wrong? Because this is not a future possibility. It is a general truth or automatic result.
This matters in transformations because students see if and immediately think will. Cambridge knows that.
Use this comparison:
| Meaning | Correct form | Example |
|---|---|---|
| General truth | present + present | If it rains, the ground gets wet. |
| Specific future possibility | present + will | If it rains tomorrow, I’ll stay home. |
| Automatic result / instruction | when + present, present | When you turn the key, the engine starts. |
✓ If you mix red and blue, you get purple.
✗ If you mix red and blue, you will get purple.
✓ When water reaches 100C, it boils.
✗ When water reaches 100C, it is boiling.
For Part 4, train this question: is the sentence about one future event, or about something that always happens? If it always happens, there is no will.
Where this appears in the exam
Part 4 gives you a complete sentence, a second sentence with a gap, and one key word. You must complete the second sentence in two to five words, including the key word unchanged.
This is where Cambridge tests whether you can control structure under limits. You cannot just write a correct sentence. You must write the only kind of sentence that fits the grammar, meaning, and word count.
A passive question often looks like this:
- Someone sent the documents yesterday.
- SENT
- The documents ______ yesterday.
The trap is tense. Many candidates write have been sent because they focus on the participle sent. But yesterday forces past simple.
✓ were sent
✗ have been sent
Reported speech questions usually force two changes at once:
- “I can’t help you today,” Sara said to me.
- TOLD
- Sara ______ help me that day.
The trap is using said me logic or forgetting backshift.
✓ told me she couldn’t
✗ told me she can’t
Inversion questions look more formal:
- I had never seen such an expensive watch.
- NEVER
- ______ such an expensive watch.
The trap is word order. If never starts the sentence, inversion is required.
✓ Never had I seen
✗ Never I had seen
Zero conditional questions are less common than passive or reported speech, but they appear when Cambridge wants to test whether you understand general truths, not future results:
- Water boils at 100C if you heat it.
- WHEN
- Water boils at 100C ______ it.
✓ when you heat
✗ when you will heat
Another trap in Part 4 is over-transforming. If the key word is TOLD, you may only need a reported structure. Do not also add extra words that change emphasis or time. The target is equivalent meaning, not style.
If you want a full overview of the exam before drilling Part 4, read what is FCE B2 First. If you are building a wider study plan, how to prepare for B2 First and how to prepare FCE Reading help you place Use of English inside the whole paper.
The scoring logic is simple but brutal: one small grammar error can make the whole answer wrong. That is why pattern recognition matters more than creativity here.
Worked examples step by step
Situation: Active sentence becomes passive.
Original: Someone built this bridge in 1890.
Key word: BUILT
✗ This bridge built in 1890 — missing was, so the passive form is incomplete.
✓ This bridge was built in 1890 — past simple passive = was + past participle.
Spanish pushes many learners to think the participle is enough because the meaning is obvious. Cambridge does not care. If the structure is passive, be must be there.
Situation: Direct speech becomes reported speech.
Original: “I will send the email tomorrow,” Jack said to me.
Key word: TOLD
✗ Jack told me he will send the email tomorrow — told takes an object correctly, but the tense and time marker do not shift.
✓ Jack told me he would send the email the next day — will → would and tomorrow → the next day after a past reporting verb.
This one is hard because the wrong answer sounds understandable. But Part 4 tests exact control, not approximate meaning.
Situation: Sentence with never at the start.
Original: I had never heard such a strange explanation.
Key word: NEVER
✗ Never I had heard such a strange explanation — no inversion after fronted negative adverbial.
✓ Never had I heard such a strange explanation — after never, use auxiliary + subject.
A good shortcut: if the sentence starts with never, rarely, hardly, seldom, check immediately for inversion. If you do not see the auxiliary before the subject, you are probably wrong.
Situation: General truth, not future possibility.
Original: The screen lights up if you press this button.
Key word: WHEN
✗ The screen will light up when you press this button — this changes the meaning toward one future event.
✓ The screen lights up when you press this button — when + present, present for an automatic result.
Spanish speakers often choose will because the result happens after the action. But zero conditional is about what always happens, not what happens later in time.
Here is one more mixed example because Cambridge likes overlap.
Situation: Passive plus tense control.
Original: They are repairing the road this week.
Key word: BEING
✗ The road is repaired this week — this sounds like a general fact or completed state, not an action in progress.
✓ The road is being repaired this week — present continuous passive = is being + past participle.
Context words matter. This week often signals a temporary ongoing action, so the passive must match that.
And one final reported example with the classic say/tell trap:
Situation: Direct speech with listener included.
Original: “I don’t like this place,” Anna said to her friend.
Key word: TOLD
✗ Anna told that she didn’t like that place — told cannot stand alone before a clause.
✓ Anna told her friend that she didn’t like that place — told + object + that-clause.
If the key word is SAID, do not force an object. If the key word is TOLD, you need one. That single rule saves a lot of marks.
Exercise: test yourself
-
Someone has stolen my phone.
STOLEN
My phone __________________________. -
“I am very tired now,” Lucy said.
WAS
Lucy said that __________________________ very tired then. -
I had rarely seen such a bad performance.
RARELY
__________________________ such a bad performance. -
If you cool water to 0C, it becomes ice.
WHEN
Water becomes ice __________________________ to 0C. -
“We will finish the project tomorrow,” they told us.
WOULD
They told us that __________________________ the project the next day.
Answers:
- has been stolen — present perfect passive = has been + V3.
- she was — present in direct speech backshifts to past after said.
- Rarely had I seen — after fronted negative adverbial, use inversion.
- when you cool it — general truth: when + present, present.
- they would finish — in reported speech, will → would.
If you want more timed Part 4 practice, try lingaly.
FAQ
How do I know if Cambridge wants passive voice in Part 4?
Look at the focus of the second sentence. If the thing receiving the action becomes the subject, you probably need be + past participle. Also check whether the original subject is unknown, unimportant, or moved into a by-phrase.
Do I always need backshift in reported speech?
Usually yes when the reporting verb is in the past, and Part 4 normally expects that standard rule. But first check the exact frame: if the sentence already gives you a present reporting verb, or the fact is still generally true, the form may stay present. For extra practice with this kind of grammar control, use these B2 Use of English exercises.
What is the fastest way to improve at key word transformations?
Stop doing them as random puzzles. Group them by pattern: passive, reported speech, inversion, conditionals. When you review, do not just mark answers right or wrong. Write the trigger that should have made you choose the structure.