Page 35 - Grasp English B1 (Grammar Book)

Workouts 5

Deduction: must, can’t

We use must to say that we are certain that something is true.
e.g.
All the lights are on; she must be at home.
It is just five o’clock. Larry must be still at the office because they don’t leave there before seven.
We use can’t to say we are sure that something is impossible.
e.g.
All the lights are off; she can’t be at home.
It is half past six. Larry can’t be at the office because they leave there after six.
Note 1: We need helping statements to make deduction sentences clearer.
e.g.
She has a very expensive sports car. She must be rich. (I think that she is rich because she has an expensive
car)
Kelly and Jemma can’t be sisters. They don’t look like each other. (I don’t think they are sisters because they
don’t look like each other)
Note 2: We cannot use can (an affirmative form of can’t) or mustn’t (the negative form of must) to express
deduction.

G. Complete the sentences with must or can’t.

1. You have just had a big slice of cake. You be hungry!
2. She has lived here for so many years. She know a lot of people!
3. He has worked hard all night. He be exhausted.
4. She makes people repeat everything they say. She be a bit deaf.
5. I wonder who is at the door. It be Larry, he is still at school.

6. He knows a lot about history. He be fond of the subject.
7. The people next door be out of town. Their shutters have been closed for three weeks.
8. It has been raining for weeks. They be missing the sunshine.
9. That hotel is always crowded. It be a very good one.

10. Mike is so ill-tempered! I am sure that he have many friends.

H. Match the sentences below.

1. He must be here. a. She’s lived in Paris for only a few weeks.
2. They’re coming today. b. It must be urgent.
3. I am sure I can’t pass the exam.
c. He can’t be abroad.
4. He has earned a lot of money so far.
d. I don’t feel very confident.
5. She can’t speak French very well.
e. I can see his car in front of the building.
6. My keys are not on my desk.
f. They must be on their way right now.
7. Someone told me that Oliver was in Poland but
I saw him yesterday. g. He must be working really hard.
8. You got the job you have been wanting for so h. He must need them urgently.
long! i. They must be in the drawer.
9. They told me to prepare the project by tomorrow. j. You must be very pleased.
10. He asked them to send the goods today.

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