Modal verbs: How to use may, might and could to talk about past possibilities

Learn how to use the past possibility modals may, might and could.

This is the second of two videos on 3 useful modal verbs that we use to talk about possibility and certainty in English. The first video was about how we use them in the present and future and you can see it here.

This video is about how we use may have done, might have done and could have done to talk about past possibilities. You’ll learn how to structure sentences with with have and the past participle.

You’ll also learn how the meaning of the phrases may not have and might not have differ from couldn’t have. And best of all you’ll see lots of examples in action in a spooky story and be invited to put them to use and create more examples of your own.

Click here to learn how we use may, might and could to talk about the present and future.
Click here to see more grammar videos.
Click here to learn how to pronounce can and can’t in British and American English.

Past possibility modals

Oh, sit Carter. Good boy.
Do you think this hotel may be haunted?
Might there be a ghost?
What do you think could happen to us?

Welcome back to our second video on three important modal verbs. In our first video we looked at how we them to talk about possibilities in the present and the future. Here’s the link. In this video we’ll show you how we use them to talk about possibilities in the past.
Before we start, I have two questions for you. First one: do these sentences all mean the same thing? Yes, they do! They all mean we think something is possible.
But is there a little difference? Well, ‘may’ is less frequent than ‘might’ and ‘could’ in conversation. And some people think ‘might’ means something is less possible than ‘could’ and ‘may’. But not everyone. Linguists love to argue about it. But for practical purposes, there is no difference. They mean the same thing.
OK, second question. Listen to me saying the first sentence in two different ways.
It could happen.
It COULD happen.
Is there a difference in meaning now?
Yes, there is. If I stress the word ‘could’ it means I think something is less possible, less certain. It’s the same with the other verbs.
It may happen. It MAY happen.
It might happen. It MIGHT happen.
Did you hear the difference? When we stress the modal verb, it means we think something is less possible, less certain.
Good. So now let’s look at possibilities in the past. Let’s check in with Jay and Carter and see what’s happening.

Hi everyone. Good to see you again. We’re still staying in this old hotel and Carter still doesn’t like it, do you boy? Carter didn’t sleep well last night. I’m not sure what was wrong but he may have eaten something that upset his stomach. And I had another bad dream last night. It was the same nightmare but this time there were two little girls. They looked the same – identical. They could have been twins. They were whispering and they both wanted to kill me. I was on the floor on my back and I couldn’t move. They were holding my arms and pulling me across the floor and laughing. It was horrible.
But here’s what’s strange. When I woke up today I found these bruises on my arms. Look! Where did they come from? I might have banged into something yesterday, but if I did, I don’t remember it. Take care everyone. I’ll talk to you later.

Sometimes things happen and we don’t know why, but we speculate and come up with possible reasons. We heard Jay doing that. He wasn’t sure why some things happened, but he had some ideas.

Carter may have eaten something that upset his stomach.
The girls looked identical. They could have been twins.
I might have banged into something yesterday.

Jay didn’t know why Carter couldn’t sleep but he thought perhaps he ate something that upset his stomach.
He didn’t know if the little girls in his nightmare were twins, but he thought it was possible.
And he also thought it was possible that he banged into something and that’s how he got the bruises. He’s not sure.
When we speculate about past possibilities, we say ‘may have’, ‘could have’ and ‘might have’.
Now, what about negative sentences. Because we can also speculate about things that might NOT have happened. Let’s go back to Jay and see how that works.

Hey everyone. We slept better last night, but I think someone might have broken into our room. Before I went to bed I shut the window. But when I woke up it was unlocked and wide open. I may not have locked it last night, but I know it was shut when I went to bed.
And I turned my computer off too. But when I got up it was on. It couldn’t have turned itself on.
And I think someone moved my water. When I go to sleep I always have a glass of water on a table on the left hand side of my bed. But when I woke up this morning, it was on the right hand side. I guess it’s possible that I might not have put it on the left side but it’s odd because I’m left handed.
And if someone broke in, I don’t understand how they didn’t wake us. Carter’s a very light sleeper. The door was locked and they couldn’t have climbed through the window because it’s too small, and this is the fourth floor. I just don’t get it. Have you got any ideas?

So some strange things happened while Jay was asleep. He shut the window before he went to bed but it was open when he woke up.

I may not have locked the window last night but I know it was shut.

So Jay definitely shut the window, but it’s possible he didn’t lock it.
And another strange thing. His glass of water was on the right hand side of his bed, not the left.

I might not have put my water on the left side, but it’s odd.

Odd means peculiar. Normally he puts his water on the left side, but did he do that last night? He’s not certain. He might have put it on the right. He might not have put it on the left.
So if we say ‘might not have’ and ‘may not have’, it means there’s doubt and uncertainty.
Now, what about couldn’t have? Well that’s different.

They couldn’t have climbed in through the window because it’s too small.

Jay thinks someone broke into his room last night. He doesn’t know how, but he’s sure they didn’t get in through the window. There’s no uncertainty there. Another example.

The computer couldn’t have turned itself on.

He doesn’t know why the computer was on, but he’s certain of one thing. The computer didn’t turn itself on. That would be impossible.
So when you’re talking about the past, use ‘couldn’t have’ to talk about impossible things – things that didn’t happen.
And use ‘might have’ and ‘may have’ to talk about things you’re not certain about – possibilities.
Easy huh? And that’s it. Now you know all the important stuff for talking about possibilities with may could and might. Do you want to try using them? Are you ready to put them to use? Then let’s see what’s going on with Jay.

Hey everyone. Just one more night in this hotel and then we’re going home. We can’t wait to leave. Uh oh. It looks like we’ve got an electrical problem here. The lights keep flickering. Carter are you OK? Who’s that? Who’s there? We’re going to kill you.

Oh my. What do you think might have happened to Jay and Carter? Pick a question and tell us what you think. Try to give as many answers as you can using ‘may’, ‘could’ and ‘might’? and write them in the comments. We’re looking forward to reading them.
If you’ve enjoyed this video, please share it with a friend. And don’t forget to subscribe to our channel. Bye everyone!

Click here to learn how we use may, might and could to talk about the present and future.
Click here to see more grammar videos.
Click here to learn how to pronounce can and can’t in British and American English.