LONGMAN ENGLISH GRAMMAR PRACTICE

11 Modal auxiliarles and related verbs

11.5 Uses of modals to express deduction

11.5A Certainty or deduction? [> LEG I I .27,11.32-33]

Study:

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1 We express certainty with be or any full verb: He is here. He lives here. He is leaving.

2 We express deduction with must be/can't be, must have been, can't/couldn't have been:

He must be at home. He can't be out. He must have been at home yesterday.

or with verbs other than be: He must live abroad. He must have lived abroad.

Write: Read these sentences and write С (= Certainty) or D (= Deduction) against each one.

1 John Wright is a man of action. C_

2 He was in the Galapagos ten years ago.

3 Now he lives in an enormous house.

4 He is writing a book.

5 He has been writing this book since he came back from the Galapagos.

6 He must be writing about his travels.

7 He must have seen the giant tortoises and the iguanas on the Galapagos.

8 He can't have seen any elephants on the Galapagos.

9 He can't have been working very hard on his book.

10 He must have taken a lot of photos while he was on the islands.

11 He must have done a lot of research for his book.

12 He must enjoy life.

11.5B Two kinds of 'must be' [> LEG 11.33,11.46-48]

Study:

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1 We use must be in the present to express deduction [> 11.1C]:

You haven't eaten for hours. You must be hungry!

2 The negative of must be (= deduction) is can't be, not "mustn't be*:

You've only just eaten. You can't be hungry again! (Not *mustn't be*)

3 We can also use must (be) to express total obligation [> 11.1A]:

This is a hospital. You must be quiet.

4 The negative of must (be) (= total obligation) is mustn't (be) (= prohibition [> 11.3B]):

You mustn't be noisy outside a hospital.

Write: a Supply must be, can't be, or mustn't be.

b Write D (= Deduction) or О (= Obligation) beside each sentence.

1 The meeting is at 10 o'clock sharp and you ШУШб.М: late. _Q_

2 You at the station ten minutes before the departure of the train.

3 The children tired already! We've only been walking for ten minutes.

4 The children thirsty. They haven't had a drink for hours.

5 Did you hear that? It someone walking about in our garden.

6 I don't recognize the handwriting on this envelope. It from anyone we know.

7 Your handwriting clear, otherwise no one will be able to read it.

8 You a nuisance when you're a guest in someone's house.

9 Don't panic! We late for the train. It doesn't leave till 10.05.

10 We late for the train or we'll miss our connection.