PAST MODALS OF SPECULATION
• For a past possibility we use could/might have+ - past participle:
They could/might have been to London. (but I'm not sure whether they were there or not)
How do we form continuous and passive forms with past modals?
We use the modal + have been + the present participle (V. ing) for continuous active forms We use the modal + have been + the past participle (V3) for passive forms.
a. He must have been planning to come back for them. (continuous active form)
b. Nobody really knows what they might have been used for: (passive form)
c. I can't have been paying attention. (continuous active form)
d. They could have been used to knit gloves. (passive form)
We can use could/might/may have + past participle or might/may have been + -ing to say that (it's possible that something was true or happened in the past.)
1. It's been three days. They could/might/may have finished painting the house by now.
2. If they left at 9, they could/might/may have already arrived.
3. She was home last night but didn't answer the door. She might/may have been having a shower.
4. I think I could/might/may have left the air conditioning on. Please can you check?
5. Police think the suspect could/might/may have left the country using a fake passport.
*We can use could have + past participle say that something was possible in the past but We can use could did not happen.
1. He could have played in the first division but had a terrible injury.
2. He could have had better jobs if he had spoken English.
3. I could have been a professional player, but I broke my leg when I was 17.
4. You could have passed your exams if you had studied as I told you!
5. He could have asked me to help him build the wardrobe, instead of spending all day doing it by himself.
1. A. What, isn't Hassan at work yet?
B. I don't know, he might have missed the train. (I am not sure)
2. Do you think she might have forgotten about the appointment? It's 9,20. (I am not sure)
3. You've been looking all morning; do you think you might have lost your keys?
• For a negative deduction about the past we use can't couldn't have + past participle,
1. You can't have vacuumed your room, it's still dirty!
2. She couldn't have revised the material because she flunked the test.
3. He can't have left, his car's here.
•We use can't/couldn't have + V3 or can't have been + V-ing to say that we are quite sure that something did NOT happen or was
NOT true in the past.
We use can't / couldn't have + V3 when we think it's not possible that something happened.
1. You can't/couldn't have seen Hassan last night. He was in hospital.
2. Rula can't/couldn't have passed the test. She didn't even open the books.
3. She can't have driven there. Her car keys are still here.
4. I thought I saw Adnan this morning but it couldn't have been him - he's in London this. week.
5. Even if I had studied for 1000 hours I could not have passed that exam! It was too difficult – impossible!
6. Wow! 100% on your exam You could not have done any better - well done!
• When we are positive about an action in the past, we use must have + V3,
to talk about what you believe is certain/ sure about the past
1. It must have been in January 1953 when grandpa met grandma in Paris.
2. Doa'a is late - she must have missed her train. (no other explanation is possible)
3. I don't have my keys - I must have left them in the kitchen.
4. The bicycle has disappeared - it must have been stolen.
We use must have + past participle or must have been + -ing to say that we are quite sure that something was true or happed in the past.
When we feel sure about what happed
1. I can't find my wallet! I must have dropped it in the taxi.
2. You must have had a real scare when you saw the crocodile.
3. He was the only victim. He must have been sleeping when the fire started.
4. The cat has escaped - I must have left the window open by mistake.
5. The thief must have had a key. The door was locked and nothing was broken.
• When we are less certain, we use may/might not have + V3.
1. Dad may not have bought bread, so let's get a loaf.
2. You'd better take your laptop because Ali might not have taken his.
Note: that we use might not or may not (NOT could not) to talk about a negative possibility.
1. He seems too calm. He might/may not be aware of the risks.
2. She might/may not have heard us. Knock again.
• We use would have + V3 when we are making as assumption about what happened in the past or drawing a logical conclusion.
1. He would have been well-off at that time. (assumption)
2. Rula would have been here earlier but her train was delayed. (assumption)
3. Maria would have graduated from school so she was able to land a well-paid job. (logical conclusion)
4. I would have called you but my phone had no battery. (logical conclusion)
5. There would have been much simpler and cheaper ways of knitting gloves. (assumption)
