What do you think… …he was? …he wore? …he ate? Where did he live? How did he die? How old was he when he died? He was probably a hunter. He could have been a warrior He might have lived in a tent He could have been 50 years old

1. What was he? (could) 2. What was he doing in the mountain? (might) 3. Where did he live? (must) 4. How did he die? (may) 5. What did he eat? (must) 6. How old was he when he died? (could)

1. He could have been a hunter/shepherd. 2. He might have looked after his sheep. 3. He must have lived in a cave. 4. He may have died in cold and starvation. 5. He must have eaten a lot of meat and berries. 6. He could have been between forty and forty-five.

Auxiliary verb + have + past participle Must have lived Might have been May have died Could have seen

 ‘Had to’: the past form of ‘must’ (didn’t have to)  ‘Must have’: refers to past certainty e.g. 1. Sorry I’m late. I had to post some letters. 2. He must have lived in a cave.

 ‘Should’ and ‘ought to’ is probably the same  ‘Should have’ refers to sth which was supposed to happen. e.g. 1. The parcel I sent you should have arrived by now. 2. You shouldn’t have eaten so much last night.

 ‘could have’: past possibility or uncertainty e.g. 1. David could have won the race if he had tried. (possibility) 2. It could have been Sue, I suppose. (uncertainty)  ‘couldn’t have’: used with comparative adjectives e.g. We couldn’t been happier in those days.

 ‘might have’: past possibility (not happen) e.g. You might have drowned!  ‘might have’/ ‘may have’: uncertainty e.g. I suppose I may have been rather critical. They might not have received our letter yet.

 Refer to the speaker’s certainty a/b a past action. e.g. Someone must have taken it. (I’m sure they did) You can’t have lost it. (I’m sure you didn’t)  Used with surely in exclamations e.g. Surely you can’t have eaten all of it. Surely you must have noticed it.

 Refers to events in the past which did not actually happen. e.g. I would have accepted the job, but I didn’t want to move house.  Assumptions a/b the past e.g. Someone called after you left but didn’t leave a message.

 ‘needn’t have’: an unnecessary action which was actually done. e.g. You needn’t have paid all at once. (You did pay)  ‘didn’t need to’: an unnecessary which was not done. e.g. I didn’t need to go to the dentist again, luckily.

They’ll have They must have arrived Certain They might have They could have They may have Possible They can’t have They won’t have Certain

You must have seen him at the cinema. I know he was there. The dog is really dirty. He might have swum in the lake. He can’t have been telling the truth. He might have left a message on your mobile. I don’t know where she is. She may have gone shopping. She must have been very upset when you told her the news. They’re not answering their phone. They must have gone away already. I don’t see their car. They can’t have come back yet.