Passive Voice with Modal Verbs: Can Be Done

To express that something is possible, necessary, or expected without saying who does it, English often uses a modal verb with the passive. Forms like can be done, must be finished, or should be checked keep attention on the action rather than the person. This pattern is common in rules, instructions, and formal statements, and seeing it in real examples makes it easier to recognize and use naturally.

How modal verbs form passive voice

When a sentence has a modal verb and you want to make it passive, the pattern is very regular: modal + be + past participle. That is the form learners need to remember. If the active sentence is “They can finish the report today,” the passive sentence is “The report can be finished today.” The modal stays the same, and the main verb changes to a past participle.

The passive is used when the action is more important than the person who does it, or when the doer is unknown, obvious, or not necessary. In everyday English, this happens a lot in rules, instructions, formal writing, work emails, and announcements: “Applications must be submitted by Friday,” “Mobile phones may be used in the lobby,” “The issue can be solved remotely.”

Three small details matter a lot:

• Use be, not another verb form: “can be done,” not “can done” and not “can to be done.”
• Use the past participle: “written,” “made,” “seen,” “built,” not the base form.
• The modal itself does not change for person or number: “I can be invited,” “She can be invited,” “They can be invited.”

Here are some common mistakes learners make:

• ❌ The room can cleaned today.
  ✅ The room can be cleaned today.
• ❌ Your bag must be pack before 8 a.m.
  ✅ Your bag must be packed before 8 a.m.
• ❌ These files should be send by email.
  ✅ These files should be sent by email.

Teacher note: If you are unsure whether a sentence is passive, look for be + past participle. That small test helps students catch many mistakes quickly.

If you want a broader overview of modal passive forms, remember that this pattern works with many modals, not only can and must.

Can be done for ability, possibility, and permission

With can be done, the meaning usually comes from the situation, not just the grammar form. It can express ability, possibility, or permission. In passive sentences, the focus is not on the person doing the action, but on what is possible, allowed, or achievable.

This form is especially common in practical English: “The form can be completed online,” “The door can be opened with a card,” “Pets can be taken on the train.” These are natural because the result or option matters more than the doer.

1. Ability means something is possible because there is enough skill, equipment, or method.

• The stain can be removed with warm water.
• This software can be installed in under five minutes.
• The problem can be fixed without replacing the whole system.

2. Possibility means something may happen or may exist as an option.

• The tickets can be bought at the station.
• The meeting can be moved to Thursday if needed.
• Some errors can be avoided with a final check.

3. Permission means something is allowed.

• Payment can be made by credit card.
• Photos can be taken after the performance.
• Guests can be seated in the garden area.

Compare these pairs carefully:

• Active: You can use the side entrance.
  Passive: The side entrance can be used.
• Active: Visitors can borrow umbrellas at reception.
  Passive: Umbrellas can be borrowed at reception.
• Active: A technician can reset the device remotely.
  Passive: The device can be reset remotely.

One useful point: passive sentences with can often sound more neutral and more formal than active ones. Compare “You can return the item within 14 days” with “The item can be returned within 14 days.” The second version is common in notices, policies, and websites.

Students also confuse passive can be done with active structures. Watch these:

• ❌ The package can deliver tomorrow.
  ✅ The package can be delivered tomorrow.
• ❌ This room can be use for meetings.
  ✅ This room can be used for meetings.
• ❌ The results can be see online.
  ✅ The results can be seen online.

If you want to compare active meanings such as ability and permission more directly, a lesson on can and could can help you see why the passive uses are so flexible.

Must be done for strong rules and obligations

Must be done is used when a rule, duty, or requirement is very strong. In passive form, it often appears in official instructions, regulations, school policies, safety notices, and workplace procedures. The sentence does not focus on who performs the action. Instead, it highlights that the action is necessary.

This form sounds firm. “All visitors must be registered at the front desk” is stronger than “All visitors should be registered.” The first one means it is required, not just recommended.

Here are typical uses:

• Seat belts must be worn during takeoff and landing.
• Homework must be submitted by midnight.
• The medicine must be kept out of children’s reach.
• Personal data must be protected under company policy.

Compare the strength in these pairs:

• The doors must be locked at 10 p.m. = this is a rule.
  The doors should be locked at 10 p.m. = this is advice or best practice.
• All receipts must be attached to the form = required.
  All receipts can be attached digitally = possible option.
• Names must be written clearly = mandatory instruction.
  Names may be written in capital letters = allowed choice.

In real communication, this passive form is common when the rule applies to everyone and the authority is understood:

• Helmets must be worn on site.
• The form must be signed before processing.
• All liquids must be placed in a clear bag.

Teacher note: Many learners overuse must in conversation. In rules and notices, it is perfect. In friendly spoken English, native speakers often choose softer forms unless the obligation is truly strong.

Common mistakes often involve weak verb forms or word order:

• ❌ The document must signed today.
  ✅ The document must be signed today.
• ❌ Safety glasses must be wear in the lab.
  ✅ Safety glasses must be worn in the lab.
• ❌ These boxes must be putted outside.
  ✅ These boxes must be put outside.

If you need a clearer sense of when must signals strong obligation, it helps to compare passive rules with everyday active sentences such as “You must wear a helmet.”

Should be done for advice and expected action

Should be done is softer than must be done. It is used for advice, recommendations, best practice, and actions that are expected in normal circumstances. This is the form you often hear in professional discussions, feedback, and polite instructions.

It does not usually mean “no choice.” Instead, it suggests the action is sensible, appropriate, or probably necessary. For example, “The report should be checked before it is sent” means checking is the right thing to do, even if it is not an absolute rule.

Typical examples:

• Your password should be changed every few months.
• The vegetables should be washed before cooking.
• The hotel room should be booked in advance during summer.
• These questions should be answered as clearly as possible.

This form can also express expectation:

• The package should be delivered by Friday.
• The final score should be announced at noon.
• The road should be reopened later this evening.

Now compare three useful contrasts:

• The essay must be handed in by 9:00. = firm deadline.
  The essay should be handed in by 9:00. = expected, recommended, but softer.
• The windows can be cleaned from outside. = possible.
  The windows should be cleaned once a month. = advisable.
• Guests may be seated after the bell. = allowed.
  Guests should be seated before the speech begins. = recommended or expected.

Learners sometimes choose should when they really mean a strict rule, or they choose must when they only want to sound helpful. Think about the speaker’s intention:

• friendly recommendation → should be done
• policy or legal requirement → must be done
• practical possibility → can be done

Common errors:

• ❌ The form should be fill in blue ink.
  ✅ The form should be filled in blue ink.
• ❌ The lights should turned off at night.
  ✅ The lights should be turned off at night.
• ❌ This issue should be discuss tomorrow.
  ✅ This issue should be discussed tomorrow.

May be done and might be done for uncertainty

When you want to show uncertainty in passive voice, may be done and might be done are very useful. Both forms suggest that something is possible, but not certain. They are common in cautious speech, academic writing, reports, news language, and polite professional communication.

In many situations, may sounds slightly more neutral or formal, while might can sound a little less certain. The difference is often small, so context matters more than grammar labels.

Examples with may be done:

• The results may be announced later this week.
• Your request may be reviewed by another team.
• Extra charges may be added in some cases.

Examples with might be done:

• The repairs might be completed by Monday if the parts arrive.
• The concert might be moved indoors because of the weather.
• A second interview might be required for this position.

These pairs show the contrast clearly:

• The problem can be solved with an update. = it is possible in general.
  The problem may be solved with an update. = this is one possible result.
• The train must be delayed for safety reasons. = required action.
  The train might be delayed by heavy snow. = uncertain situation.
• The message should be sent tonight. = recommendation.
  The message may be sent tonight. = perhaps it will happen.

A practical detail: may be is different from maybe. In passive grammar, you need the two-word verb phrase may be.

• ❌ The event maybe canceled.
  ✅ The event may be canceled.
• ❌ The order might be ship tomorrow.
  ✅ The order might be shipped tomorrow.
• ❌ A refund may given in special situations.
  ✅ A refund may be given in special situations.

Teacher note: If students are deciding between can, may, and might, I ask one question: “Are you talking about a real ability, a permission, or an uncertain possibility?” That usually leads them to the right choice.

For a wider comparison of modals in passive, it helps to see how each modal changes the speaker’s attitude rather than the grammar structure.

Negative modal passive forms: cannot be done

Negative forms follow the same basic pattern: modal + not + be + past participle. With can, the usual full form is cannot be done, though can’t be done is common in speech and informal writing. These forms are used when something is impossible, not allowed, not recommended, or not expected, depending on the modal.

The modal changes the meaning of the negative sentence. Compare “cannot be used,” “must not be used,” and “should not be used.” All are negative, but they are not the same.

Notice these important contrasts:

• The machine cannot be repaired. = it is impossible or not workable.
• The machine must not be repaired without disconnecting the power. = repairing it in that condition is forbidden.
• The machine should not be repaired by an untrained user. = strong advice against it.

More examples:

• The online form cannot be submitted without an email address.
• Food must not be brought into the exam room.
• The bottle should not be stored in direct sunlight.
• The appointment may not be confirmed until tomorrow.

Here are frequent learner errors:

• ❌ This password cannot used again.
  ✅ This password cannot be used again.
• ❌ The laptops must not be leave in the car.
  ✅ The laptops must not be left in the car.
• ❌ The soup should not be eat after two days.
  ✅ The soup should not be eaten after two days.

One more language point: in formal writing, cannot is usually one word. “Can not” is much less common and is only used in special cases for emphasis.

Questions with modal passive word order

Questions are straightforward once you know the statement form. Put the modal first, then the subject, then be + past participle. So the pattern is: Modal + subject + be + past participle? For example: “Can the invoice be emailed?” or “Should the batteries be replaced now?”

This word order is especially useful in service situations, meetings, and polite requests for information. It allows you to ask about possibility, rules, permission, timing, and procedure without focusing on who does the action.

Examples with yes/no questions:

• Can this form be completed on a phone?
• Must all guests be checked in before 6 p.m.?
• Should the package be insured for international shipping?
• Might the deadline be extended if the system fails?

Examples with question words:

• When can the room be cleaned?
• How should the data be organized?
• Where may the car be parked?
• Why must the form be printed twice?

Compare active and passive question forms:

• Active: Can we cancel the booking?
  Passive: Can the booking be canceled?
• Active: Should they update the website?
  Passive: Should the website be updated?
• Active: Must staff wear ID cards?
  Passive: Must ID cards be worn by staff?

Common mistakes often come from mixing active and passive word order:

• ❌ Can be the tickets collected at the desk?
  ✅ Can the tickets be collected at the desk?
• ❌ Should be this email answered today?
  ✅ Should this email be answered today?
• ❌ Must the windows closed before leaving?
  ✅ Must the windows be closed before leaving?

Teacher note: In class, I often tell students to build the question in two steps: first say the modal question, then add be + participle. For example, “Can the file... be opened?” This prevents word-order mistakes.

Modal passive vs normal passive tense forms

Learners often confuse modal passives with ordinary passive tenses because both use be + past participle. The difference is this: ordinary passive forms show a tense directly, while modal passives show a modal meaning such as possibility, obligation, advice, or uncertainty.

Compare “The order is shipped every day” with “The order can be shipped today.” The first sentence is a present simple passive fact or routine. The second adds a modal idea: it is possible or available today.

Three comparison pairs can help:

• The rooms are cleaned every morning. = routine.
  The rooms must be cleaned before guests arrive. = requirement.
• The documents were sent yesterday. = completed past action.
  The documents can be sent tomorrow instead. = option or possibility.
• The food will be served at eight. = future plan.
  The food should be served hot. = recommendation.

Another question learners ask is whether modal passives have tense. Strictly speaking, the modal itself does not work like a normal tense form. Instead, it adds meaning. Time usually comes from context or from other words:

• The report can be finished today.
• The forms must be returned by Friday.
• The package might be delivered tomorrow morning.

If you are still sorting out the bigger system, a full modal verb guide can help you separate meaning from tense more clearly.

Practice: choose the right modal passive

Try these tasks slowly and say the sentences aloud if possible. That helps you hear whether the form matches the meaning. Each block tests a different skill: choosing meaning, transforming structure, and correcting errors.

Do not rush to the answers. First decide what the sentence needs: possibility, obligation, advice, uncertainty, or prohibition. Then check the grammar pattern: modal + be + past participle.

Practice block 1: Choose the correct form

1. The application (can be completed / must be completed) online, but paper copies are not accepted.
2. Safety helmets (should be worn / must be worn) on this construction site. It is a legal requirement.
3. The train (may be delayed / should be delayed) because of heavy fog.
4. This password (cannot be reused / should not be reused) because the system blocks old passwords completely.
5. Guests (can be seated / must be seated) in the lounge while they wait; it is available to them.
6. The medicine (must be taken / may be taken) with food, according to the doctor’s instructions.
7. The final draft (should be checked / might be checked) one more time before you send it.
8. The meeting room (can be booked / must be booked) through the staff app if you want to use it.
9. Large bags (must not be brought / may not be brought) into the museum. They are prohibited.
10. The results (might be published / must be published) later this evening, but no one is sure yet.

Practice block 2: Rewrite in the passive with a modal

1. You can download the receipt after payment.
2. Staff must store chemicals in locked cabinets.
3. You should wash these berries before eating them.
4. The organizers may cancel the outdoor class.
5. You cannot open this file without special software.
6. Visitors must not feed the animals.
7. We might move the interview to next week.
8. You should answer all essay questions in full sentences.
9. The hotel can arrange airport pickup on request.
10. Passengers must show boarding passes at the gate.

Practice block 3: Spot and correct the error

1. The report can finished by noon.
2. Must be all forms signed at the desk?
3. This button should not be press repeatedly.
4. The reservation may canceled if payment is late.
5. Can the bikes be rent by the hour?
6. Mobile phones must not used during the exam.
7. The package might be deliver tomorrow.
8. Should the lights turned off before we leave?
9. The old version cannot be install on this computer.
10. Where must be the keys returned?

FAQ: modal passive voice

1. Can I use a modal passive without saying who does the action?

Yes, and that is one of the main reasons to use it. “The form must be signed” is complete even if you do not say who signs it. If the doer matters, you can add it later: “The form must be signed by a parent.”

2. Is “can be done” always passive?

Yes, if done is the past participle and the sentence means something receives an action. “It can be done today” is passive. But not every sentence with can be is passive. “She can be noisy” is not passive because noisy is an adjective, not a past participle.

3. What is the difference between “must not be done” and “cannot be done”?

Must not be done means prohibited. Cannot be done means impossible or not possible in the situation. Compare: “The machine cannot be moved without a crane” and “The machine must not be moved while it is running.” One is about impossibility; the other is about a rule.

4. Can I use contractions in modal passive sentences?

Yes, in informal English. “It can’t be fixed today” and “The bill shouldn’t be paid twice” are natural in conversation and emails. In formal notices, manuals, or academic writing, full forms such as cannot and should not are often better.

5. Do I always need the word “be” after a modal in passive voice?

Yes. That word is essential. Without it, the sentence is incomplete or incorrect. Say “The room may be cleaned later,” not “The room may cleaned later.” This is one of the most common learner mistakes.

6. Are modal passives common in spoken English, or only in writing?

They are common in both, but the situations differ. In writing, they often appear in rules, policies, and instructions. In speaking, they are frequent in discussions about options and procedures: “Can it be changed?” “Should this be printed?” “Must it be done today?”

7. Can I use adverbs inside a modal passive?

Yes. Adverbs usually go after be or before the past participle, depending on the adverb and style: “The files can be easily shared,” “The order must be carefully checked.” In natural English, short adverbs often fit well between be and the participle.

8. How can I choose the right modal quickly during an exam or conversation?

Ask yourself what meaning you need first. If it is possible, use can. If it is a strict rule, use must. If it is advice, use should. If it is uncertain, use may or might. After that, build the form automatically: modal + be + past participle. That habit makes modal passive sentences much easier to produce correctly.