Identify the correct passive voice form of the following sentence:-
One should keep one's promises.
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → Promises should be kept.
Passive with a modal and a general subject:
| Change | Active | Passive | Why |
|---|---|---|---|
| Object becomes subject | one’s promises | Promises | The object one’s promises becomes the subject “Promises”. |
| Tense kept | should keep | should be kept | Modal + base form becomes modal + be + past participle: “should keep” becomes “should be kept”. |
| Agent (by ...) | One | – (left out) | “One” is a general subject (anybody), so the by-phrase is left out. |
| Full sentence | One should keep one’s promises. | Promises should be kept. |
Example: One must obey the law. → The law must be obeyed.
Why the Other Options are Incorrect?
Option 1: Promises need to be kept. — Incorrect. The modal "should" is replaced by "need to", which changes the verb of the original.
Option 3: Nobody keeps promises. — Incorrect. It is an active sentence with a different meaning.
Option 4: One has kept one's promises. — Incorrect. It is still active, and the tense changes to the present perfect.