She Must Be Exhausted
Modal verbs for deduction — must, can't, might, could (present and past). Jess hasn't messaged for three days. The group works out where she might be — and gets a bibimbap photo from Seoul.
📖 Reading: Where Is Jess?
Jess has not responded to any messages for three days. Maya is worried.
"She must be travelling," says Leo. "She's always flying somewhere for work."
"She can't be ignoring us," says Priya. "That's not like her at all."
"She might have lost her phone," suggests Omar. "Or it could have broken."
"She must have mentioned something," says Maya, scrolling back through old messages. "Here — she said she might be going to a conference in Seoul."
"That would explain it," says Leo. "She could be in a very different time zone. She might not even know what time it is here."
"She must be exhausted," says Priya. "Seoul is fourteen hours ahead of Toronto."
"She can't have forgotten us entirely," says Maya.
"Of course not," says Leo. "She might just be too busy to check her phone."
At that moment, Maya's phone buzzes. It's a photo from Jess — a bowl of bibimbap with the message: "Seoul is incredible. Miss you all. Back Friday."
"She must have been having the time of her life," says Leo with a smile.
"She might have sent this on her way to another meeting," laughs Omar.
"She's Jess," says Maya simply. "She could be anywhere."
🔑 Vocabulary Box
Eight key words from this lesson.
| Word | Meaning | Note |
|---|---|---|
| deduce | To reach a conclusion through reasoning from evidence | v. — We can deduce that she's travelling. |
| scroll | To move through content on a screen | v. — Maya scrolls through old messages. |
| conference | A large formal meeting, usually professional | n. — Jess might be at a conference in Seoul. |
| time zone | A region of the globe that has a uniform standard time | n. — Seoul is in a different time zone. |
| bibimbap | A Korean dish of rice with vegetables, meat, and egg | n. — She sends a photo of bibimbap. |
| entirely | Completely; in every way | adv. — She can't have forgotten us entirely. |
| speculation | The action of theorising without firm evidence | n. — Their conversation is all speculation. |
| ignore | To deliberately pay no attention to someone | v. — She can't be ignoring us. |
📚 Key Verbs & Structures in This Lesson | |
must be/have (strong deduction +) | She must be tired. / She must have been travelling. |
can't be/have (strong deduction -) | She can't be ignoring us. / He can't have forgotten. |
might/could/may be (possibility) | She might have lost her phone. / She could be in Seoul. |
would explain it | That would explain why she hasn't replied. |
📚 Grammar Focus
📚 Deduction Modals — Present | |
must be (certain +) | She must be in Seoul. (I'm quite sure of it) |
can't be (certain -) | She can't be ignoring us. (I'm sure she's not) |
might/could/may be (possible) | She might be travelling. / She could be busy. |
Deduction Modals — Past
📚 Deduction Modals — Past | |
must have + pp (certain +) | She must have been travelling. (I'm sure) |
can't have + pp (certain -) | She can't have forgotten us. (I'm sure she hasn't) |
might/could have + pp (possible) | She might have lost her phone. / She could have been in a meeting. |
Degrees of Certainty
📚 Degrees of Certainty | |
100% certain + | She IS in Seoul. (we know for sure) |
90% certain + | She must be in Seoul. (strong deduction) |
50% certain | She might/could be in Seoul. (possible) |
90% certain - | She can't be in Seoul. (strong negative deduction) |
🎭 Dialogue: I Wonder What's Going On
Omar is late for once. Leo, Maya, and Priya theorise — until Omar walks in and confirms the most ordinary explanation possible.
Omar hasn't shown up today. That's strange.
He must have forgotten. He's been very stressed with exams.
He can't have forgotten — he confirmed yesterday.
He might be stuck in traffic. Or he could have overslept.
His lights were off when I walked past his building. He must have left early.
Or he might have stayed at the library last night.
He can't have done that — the library closes at 10.
[walks in] Sorry I'm late. The subway must have broken down again.
Practice Exercises
3 questionsNew exercises to reinforce what you learned. Different from the lesson material.
What does Leo suggest might explain Jess's silence?
What evidence does Maya find about Jess's plans?
What does Priya deduce about Jess's state of mind?
Practice Exercises
3 questionsNew exercises to reinforce what you learned. Different from the lesson material.
Choose: 'She hasn't answered for three days. She ___ very busy.' (strong positive deduction)
Choose: 'He speaks English perfectly. He ___ a native speaker or has lived abroad for a long time.' (strong + deduction)
Choose: 'She said she was coming at 8. It's now 9. She ___ lost.' (possibility)
🎭 Now It's Your Turn — Role Play
Practice with a partner. Use the dialogue as a model and extend it.
- Student A: Describe a mysterious situation (a neighbour you never see, a colleague who seems very stressed, a friend who suddenly changed).
- Student B: Make deductions using must be, can't be, might be, could be, must have, might have.
- Then swap. The "correct" answer is revealed at the end — how close were the deductions?