Form the passive with modal verbs using modal plus be plus the past participle for present or future situations, as in the contract must be signed by both parties, and modal plus have been plus the past participle for past deductions, as in the flight could have been delayed.
Grammar Rule
For present or future situations, use modal + be + past participle. For past situations, especially deductions, use modal + have been + past participle.
Passive Voice with Modal Verbs: Rules and Examples
| Time | Structure | Example |
|---|---|---|
| Present / future | modal + be + past participle | The contract must be signed by both parties before Friday. This issue should be resolved as soon as possible. |
| Past (deduction) | modal + have been + past participle | The flight could have been delayed because of the storm. The budget must have been approved last week. |
Remember: modal + be + past participle (present/future); modal + have been + past participle (past).
Practice Test
Instructions
Answer each question in the test below forming the correct passive sentence with a modal verb. You will get a new random set of questions every time you retake the test, plus a downloadable results summary with your name and score at the end.
Passive Voice – Modal Verbs
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Frequently Asked Questions
How do you form the passive with a modal for present or future?
Use modal plus be plus the past participle, as in the contract must be signed by both parties before Friday.
How do you form the passive with a modal for a past deduction?
Use modal plus have been plus the past participle, as in the flight could have been delayed because of the storm.
What is the difference between must be and must have been?
Must be refers to a present or future obligation or certainty, while must have been refers to a deduction about something in the past.
Can this structure express both obligation and deduction?
Yes, depending on the modal and the time reference, it can express obligation, advice, possibility, or deduction in the passive voice.