Choose the correct passive form of the given sentence:
The monkeys must have eaten the mangoes in our garden.
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → The mangoes in our garden must have been eaten by the monkeys.
Passive of “must have” + verb:
| Change | Active | Passive | Why |
|---|---|---|---|
| Object becomes subject | the mangoes in our garden | The mangoes in our garden | The mangoes receive the action, so they become the subject. |
| Modal form kept | must have eaten | must have been eaten | “Must have eaten” is a sure guess about the past. In the passive it becomes must have been + past participle (V3). |
| Agent (by ...) | The monkeys | by the monkeys | The monkeys are named, so the doer comes after “by”. |
| Full sentence | The monkeys must have eaten the mangoes in our garden. | The mangoes in our garden must have been eaten by the monkeys. |
Other modals work the same way: could have + V3 → could have been + V3, might have + V3 → might have been + V3. Example: Someone might have moved my bicycle. → My bicycle might have been moved.
Why the Other Options are Incorrect?
Option 2: The mangoes in our garden must have eaten by the monkeys. — Incorrect. The word “been” is missing. Without it, the mangoes seem to do the eating.
Option 3: The mangoes in our garden had been eaten by the monkeys. — Incorrect. “Must” is dropped. The sentence now states a fact, not a sure guess.
Option 4: The mangoes in our garden must be eaten by the monkeys. — Incorrect. “Must be eaten” is the passive of “must eat”. It talks about now, not a guess about the past.