How to Use Modal Verbs in the Passive Voice
Modal verbs—such as can, could, may, might, shall, should, will, would, must, and ought to—are commonly used to express ability, possibility, permission, necessity, and obligation. In English grammar, these verbs can also be used in the passive voice, a construction that emphasizes the action or the receiver of the action rather than the doer. Understanding how to use modal verbs in the passive voice is essential for clear and flexible expression in both spoken and written English.
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To form the passive voice with a modal verb, follow this structure:
modal + be + past participle.
For example:
The report must be finished by Monday.
The work can be completed tomorrow.
In this construction, the subject of the sentence receives the action. It is especially useful when the agent (the one performing the action) is unknown, irrelevant, or obvious from the context. For instance:
Mistakes could be made during the process.
(The focus is on the possibility of mistakes, not on who makes them.)
For modals referring to the past, the structure is slightly different:
modal + have been + past participle
Examples include:
The documents should have been submitted earlier.
The package might have been lost in the mail.
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This variation is used when expressing opinions, criticisms, or speculations about past actions.
Using modal verbs in the passive voice is also common in formal and academic writing, where the actor is often less important than the action or result. For instance:
New policies will be implemented next year.
This shifts the emphasis to the policy change rather than the people responsible.
It is important to match the modal and passive construction accurately to ensure grammatical correctness. For example, avoid incorrect forms like “The task can finished” or “The letter should be send”. The correct versions would be “The task can be finished” and “The letter should be sent.”
In summary, using modal verbs in the passive voice allows speakers and writers to highlight the action and de-emphasize the doer. It enhances clarity, politeness, and objectivity, especially in professional or formal contexts. With consistent practice, mastering this structure can significantly improve your fluency and range in English communication.