Past Modals for Speculation and Deduction

Speculation and Deduction

1. Past Modals NEF Upper-Intermediate 4B

2. must/may/might/can’t/couldn’t + have + past participle To make deductions or speculate about past actions Positive certainty Negative certainty must can’t may might could may could couldn’t

3. I must have passed the exam. I’m sure I got all the answers right You must have seen something. You were there when the robbery happened must have Use must have + past participle when you’re almost sure that something happened or was true:

4. Somebody might/may/could have stolen your bag when you were getting off the train He still hasn’t arrived. I may/might/could have not given him the right directions might/may/could have Use might/may/could have + past participle when you think it’s possible sure that something happened or was true:

5. They can’t have gone to bed yet. It’s too early. They couldn’t have seen us. It was too dark. can’t/couldn’t have Use can’t/couldn’t have + past participle when you’re almost sure that something didn’t happen or that it’s impossible

6. C ommon Mistakes may not, might not vs. couldn’t Compare: He might/may not have done it (= maybe he didn’t do it) He couldn’t have done it (= it is impossible that he did it)

7. Must + infinitive vs. Must + continuous infinitive Compare: He must work really hard. He never gets home before 9.00 pm (= deduction about a habitual action) There’s a light on in his office. He must still be working (= deduction about an action in progress at the moment of speaking) Modal Verbs for speculation and deduction: common mistakes

8. We should have gone home earlier last night. I’m exhausted now . should /ought to have Use should/shouldn’t have + past participle to express regret or criticism Ought to /oughtn’t to have + past participle is an alternative. We ought to have gone home earlier last night.

9. Other resources for speculation

10. Adjectives for Speculation bound, sure, likely/unlikely - be bound/be sure + infinitive 🡪 something is certain to be true or to happen. He’ s bound/sure to be here in a minute. He left an hour ago Subject + be likely/unlikely + infinitive, or it is likely/unlikely + that + clause 🡪 something is possible to be true or to happen. I think she’ s likely/unlikely to agree to our proposal It’ s likely/unlikely that she will agree to our proposal

11. Adverbs for Speculation - definitely 🡪 something is certain to be true or to happen. She’ll definitely pass the exam. She’s worked really hard. She definitely won’t pass the exam. She hasn’t done any work at all - probably 🡪 something is possible to be true or to happen. The painting probably isn’t genuine. It rather looks like a fake. He’s probably British. His taste in combining colours in clothes is just horrible.

12. Adverbs for Speculation definitely, probably Position: - positive sentences, before a main verb and after the auxiliary. She’ll definitely pass the exam - negative sentences, before the auxiliary verb. She definitely won’t pass the exam - After be in positive sentences, before be in negative sentences. He’s probably British The painting definitely isn’t genuine.

13. Be likely to / will probably They are very similar in meaning, but be likely to is more formal. Likely is an adjective, probably is an adverb. The new coach is likely to be appointed today The new coach will probably be appointed today