B1 | Grammar | 12 min

Making guesses: must, might and can't

Use must / might / can't to guess about something that is true right now, based on the clues you see.

How sure you are	Modal	Example
Almost sure it is TRUE (about 95%)	must	The bakery window is full of people. The bread must be fresh.
Not sure, maybe (about 50%)	might / may / could	Ken isn't in the kitchen. He might be in the garden.
Almost sure it is NOT true (about 5%)	can't	Ben has a very small kitchen. He can't be cooking for forty people.

95% / 50% / 5% show how sure you are that the sentence is TRUE.

1. Something happening now: modal + be + V-ing. The oven is on and I can smell cake. Somebody must be baking.

2. A state: modal + be / have / like ... She might have a cold.

3. Almost sure it is not true: use can't, NOT mustn't. Wrong: "He mustn't be at home." Right: He can't be at home. (mustn't is for things that are not allowed: "You mustn't smoke here.")

4. In this lesson, must means "I am almost sure". It is different from must for rules and duties (You must wear a helmet.).

Read the clues, then choose the right word for each blank.

1. A long line of people waits outside the new noodle shop every evening. The noodles ___ be very good. (about 95% sure)

____ a. can't ____ b. must ____ c. might

2. You can smell garlic and hear a hot pan in the kitchen. Someone ___ be cooking dinner. (about 95% sure)

____ a. must ____ b. might ____ c. can't

3. It is 12:30 and Nam is not at his desk. He ___ be at lunch, but you don't know. (about 50% sure)

____ a. must ____ b. can't ____ c. might

4. Mai is vegetarian. She never eats meat. She ___ be eating beef noodles. (about 5% sure)

____ a. mustn't ____ b. can't ____ c. might

5. The cafe has a sign: 'Closed on Mondays.' Today is Monday. The cafe ___ be open. (about 5% sure)

____ a. can't ____ b. must ____ c. might

6. The lights in the restaurant are off, but the front door is open. The owner ___ be inside, but you can't see anyone. (about 50% sure)

____ a. can't ____ b. may ____ c. must

7. Tuan has eaten nothing since breakfast and it is 3 p.m. He ___ be very hungry. (about 95% sure)

____ a. must ____ b. might ____ c. can't

8. Linh says she hates spicy food. She ___ like this very spicy soup. (about 5% sure)

____ a. might ____ b. must ____ c. can't

Read the clues, then type must, might or can't in each blank.

1. Bao has chocolate all over his face and hands. He ____ be the one who ate the cake. (about 95% sure)

2. Hanh never eats chocolate because it makes her ill. She ____ be the person who took the chocolate cake. (about 5% sure)

3. The back door is open. A neighbor ____ be inside the house, but you can't see anyone. (about 50% sure)

4. Dung left the party at 6 p.m. and the cake arrived at 7 p.m. He ____ be the one who ate it. (about 5% sure)

5. Mrs. Tam has made this soup every day for thirty years. Her soup ____ be very good. (about 95% sure)

6. Lan saw someone in a red coat near the kitchen. It ____ be Trang, but two other guests have red coats too. (about 50% sure)

7. The coffee machine is switched off and there are no cups on the tables. The cafe ____ be open today. (about 5% sure)

Grammar: Making Guesses with Must, Might and Can't

Making guesses: must, might and can't

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