PRESENTAModal verbs of deduction and speculationCIÓN PIZARRA MAGNÉTICA

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.

Past Modals How to use past modals? Speculation, deduction and regrets.

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

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

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.