Grammar: ⚙️ Verbs in Depth: 🎭 Modals & 🌱 Non-Finite Verbs (Advanced) (B2) - Lesson 4: Passive Voice with Modals (The work must be finished.)

✨ Lesson 4: Passive Voice with Modals

You have mastered the Passive Voice across different tenses, and you know how to use modal verbs¹. Now, we will combine these two powerful structures. The Modal Passive is very common in formal situations like rules, instructions, and official announcements, where the action is more important than who does it.

The Structure: A Simple, Consistent Pattern

The best news is that the structure for the modal passive is always the same, regardless of the modal verb you use. The modal is always followed by 'be' and the past participle.

Formula: Subject + Modal + be + Past Participle

Active: "You must finish the report by 5 PM."

Passive: "The report must be finished by 5 PM."

Common Uses with Different Modals

Let's see how this structure works with different modal verbs to express different meanings.

Obligation² (must, have to):
"Helmets must be worn by all drivers."

Advice (should):
"This temple is ancient and fragile³. It should be respected."

Possibility (can, might):
"More information can be found on our website."

Prohibition (mustn't):
"Valuables mustn't be left unattended⁴."

The Past Modal Passive

To talk about these ideas in the past, we use a slightly different structure. This is often used to express regret or make deductions about the past.

Formula: Subject + Modal + have been + Past Participle

• Past Deduction: "The window is broken. It must have been broken last night."
• Past Regret/Criticism: "The room is still dirty. It should have been cleaned this morning."
• Past Possibility: "The project failed. More money could have been invested."

🧠 Practice Quiz: Form the Modal Passive

Complete the sentences with the correct modal passive form of the verbs in brackets.

1. This important form _______ (must / sign) by the manager.
   Answer: must be signed
2. The problem is difficult, but I believe it _______ (can / solve).
   Answer: can be solved
3. You left your phone on the cafe table! It _______ (could / steal)!
   Answer: could have been stolen (This is a past possibility).
4. According to the school rules, uniforms _______ (must / wear) every day.
   Answer: must be worn
5. The meeting room was messy. It _______ (should / clean) after the last meeting.
   Answer: should have been cleaned (This is past advice/criticism).

📝 Homework: Rewrite the Rules

Rewrite these active sentences in the passive voice. The new subject is given.

1. Active: You must wear shoes inside the temple.
   Passive: Shoes ________________ inside the temple.
   Answer: Shoes must be worn inside the temple.
2. Active: Someone should clean this whiteboard.
   Passive: This whiteboard ________________.
   Answer: This whiteboard should be cleaned.
3. Active: Someone could have stolen my bicycle from here.
   Passive: My bicycle ________________ from here.
   Answer: My bicycle could have been stolen from here.

Vocabulary Glossary

1. Modal Verb: (Noun Phrase) - កិរិយាស័ព្ទគន្លឹះ (kĕ'rĭ'ya'sâp kôn'lœ̆h) - A special verb (like must, should, can) that changes the meaning of the main verb. ↩
2. Obligation: (Noun) - កាតព្វកិច្ច (ka'tâp'vĕ'kĕch) - Something that you must do because of a rule or law. ↩
3. Fragile: (Adjective) - ផុយស្រួយ (phoy'sruəy) - Easily broken or damaged. ↩
4. Unattended: (Adjective) - ដែលគ្មានអ្នកดูแล (dael k'mean neăk'dulae) - Not being watched or looked after. ↩
5. Passive Voice: (Noun Phrase) - ប្រយោគកម្មវាចក (brâyoŭk kâm'mâ'véa'chôk) - A sentence where the subject receives the action of the verb. ↩