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Verbs-Deduction - must, can't, may and might-Lesson

Deduction - must, can't, may and might (Verbs)

 
     
          
  1. Look at this example of must:

John has worked all day. He must be tired. (= I assume, believe he is tired)

We use must because we feel 100% certain that John is tired.

Here are some more examples:

– Sarah is a bank manager. She must earn a lot of money.

– Colin hasn't eaten since breakfast. He must feel hungry.

 

  1. If we are not completely certain, we use may, might or could. It is possible that it is true:

– Harriet isn't at school. She may be ill. (= I'm not sure that she is ill but it is 70% possible)

– Bianca often goes to France. She might have a boyfriend there: (= I am not sure, but it is 40% possible that she has a boyfriend there)

 

We use could to show that something is possibly true. It is less certain than may and might:

– She could have a boyfriend there.

 

  1. If we think that something is impossible or very surprising, we use can't:

– He has eaten six hamburgers. He can't be hungry. (= I think it is impossible that he is hungry)

– I don't believe it. It can't be six o'clock! (= I am very surprised)

 

  1. If we are 100% certain that something happened in the past, we use must have + past participle of the verb:

– The sun is shining but the ground is wet. It must have rained last night.

– He has arrived early. He must have driven very fast.

 

  1. We can use may have/might have/could have + past participle to show that something perhaps happened in the past:

– The plane is late. It may have been foggy at the airport.

– The money has disappeared. Ted might have stolen it.

– I didn't see Tom at the party. He could have gone home early.

 

  1. We can use can't have + past participle when we think that something in the past was not possible or was very surprising:

– He hasn't got a driving licence. He can't have driven to London.

– She doesn't know French. She can't have understood the film.

– I don't believe it! Harry can't have escaped from prison.

 

Click here for Exercise-1

Exercise-2

Exercise-3

Exercise-4