Grammar » B1+ Grammar lessons and exercises » Past modal verbs of deduction
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  • Past modal verbs of deduction

    Exercise 1

    Choose the correct option for each gap below.

    1 Nobody knows exactly why he died. But we think it been an accident.

    2 I revised more for the exam. I was lazy, and now I'll fail!

    3 Sarah looked very happy. She passed her driving test.

    4 I didn't know you were going to Phil's party yesterday. You told me!

    5 I can't believe Jim hasn't arrived yet. He taken the wrong train.

    6 I can't believe Jim hasn't arrived yet. He taken the correct train.

    7 You been ill yesterday. Jessie saw you at the bowling alley.

    8 I don't know where they went but they gone to Paris or Marseille.

    9 You paid more attention. Now we are lost.

    10 The window was broken, so the thieves got in through that window.


     

  • Past modal verbs of deduction – Grammar chart

    Past modal verbs of deduction

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    Modal verbs of deduction and speculation

    We can use some modal verbs + infinitive to talk about how certain we are that something is or is not true. We can also use some modal verbs + have + past participle to talk about how certain we are that something was or was not true in the past.
     

    Must have done

    We use must have + past participle to say that we are quite sure that something was true or happened in the past.

    • I can’t find my wallet! I must have dropped it in the taxi.
    • You must have had a real scare when you saw the crocodile. 

     

    Can’t have done

    We use can’t/couldn’t have + past participle to say that we are quite sure that something did NOT happen or was NOT true in the past.

    • You can’t/couldn’t have seen John last night. He was in hospital. 
    • She can’t/couldn’t have passed the test. She didn’t even open the books. 

    Note that for negative deduction we use can’t (NOT mustn’t)

    • He can’t be that famous. (NOT He mustn’t be that famous.)

     

    Could/might/may have done

    We use might/may have + past participle to say that it’s possible that something was true or happened in the past.

    • It’s been three days. They might/may have finished painting the house by now. 
    • If they left at 9, they might/may have already arrived.

    Note that we use might not or may not (NOT could not) to talk about a negative possibility.

    • She might/may not have heard us. Knock again. 

     

    Should/ought to have done

    We use should have/ought to have + past participle to talk about a situation expected to happen in the past. This form is normally used for criticism.

    • You should/ought to have already packed your things. We’re going to be late. 
    • He should/ought to have studied more. Nobody fails if they study. 
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