Use may or might to say that something is possibly true now, and may have or might have (done) to say that it was possibly true in the past; could works in the positive, while couldn't means something quite different.
A may and might: perhaps it is true
You are looking for Ruth. Nobody knows where she is, although everybody has a theory:
- She may be in the staffroom. (= perhaps she is in the staffroom)
- She might be having a cigarette outside. (= perhaps she is having one)
- Ask Kevin. He might know. (= perhaps he knows)
We use may or might to say that something is possible. In this meaning you can use either; there is no difference worth arguing over.
The negative forms are may not and might not.
| Subject | may / might | (not) | Verb |
|---|---|---|---|
| I / you / he (etc.) | may | (not) | be (true / in the staffroom) |
| might | be -ing (doing / working / having) | ||
| know / work / want (etc.) |
Note the difference between may be (two words: may + verb) and maybe (one word: perhaps).
- It may be true. / It might be true. (= perhaps it is true)
- Kevin might know. / Kevin may know.
- It may not be true. (= perhaps it isn't true)
- Kevin might not know. (= perhaps he doesn't know)
- "Is the café open on Sundays?" "Maybe. I'm not sure."
B may have and might have (done): perhaps it happened
For the past, we use may have or might have + past participle.
| Subject | may / might | (not) | have | Past participle |
|---|---|---|---|---|
| I / you / he (etc.) | may | (not) | have | been (asleep / at home) |
| might | been -ing (doing / working / feeling) | |||
| known / had / wanted / left (etc.) |
- "I wonder why Marcus didn't open the door." "He may have been in the bath." (= perhaps he was)
- "I can't find my car keys anywhere." "You might have left them in your coat." (= perhaps you left them there)
- "Why wasn't Holly at choir practice?" "She might not have known about it." (= perhaps she didn't know)
- "Why was Uncle Rob so quiet at lunch?" "He may not have been feeling well." (= perhaps he wasn't feeling well)
C could, may not and couldn't
Could is similar to may and might in the positive.
Couldn't, however, is not the negative of may and might. It says that something is not possible, which is a much firmer claim than may not or might not.
| Sentence | Meaning |
|---|---|
| Jamal couldn't have read my email. He would have answered by now. | It is not possible that he read it. |
| Why hasn't Jamal answered? I suppose he might not have read my email. | It is possible that he did not read it. Perhaps he did, perhaps he did not. |
- It sounds unlikely, but it could be true. (= it is possible that it is true)
- You could have left your keys in your coat. (= it is possible that you left them there)
Exercises
29.1 Complete the conversations. Choose from the box.
may be Leanne'smay not be feeling wellmay not be possiblemight be in the shedmight be Polishmight be drivingmight have onemight know
A: Do you know where Grandad is? B: I'm not sure. He might be in the shed.
Do you know where Grandad is? I'm not sure. He might be in the shed.
A: Is there a cash machine near here? B: I'm not sure, but ask the man in the paper shop. He .
Is there a cash machine near here? I'm not sure, but ask the man in the paper shop. He might know.
A: Where is that couple at the next table from? B: I've no idea. They .
Where is that couple at the next table from? I've no idea. They might be Polish.
A: Can you get me a seat on Saturday's coach? B: I'll try, but it .
Can you get me a seat on Saturday's coach? I'll try, but it may not be possible.
A: Whose umbrella is this? B: It isn't mine. It .
Whose umbrella is this? It isn't mine. It may be Leanne's.
A: Why isn't Mum answering her phone? B: She .
Why isn't Mum answering her phone? She might be driving.
A: Do you know anybody with a ladder I could borrow? B: Dave , but I'm not sure.
Do you know anybody with a ladder I could borrow? Dave might have one, but I'm not sure.
A: Lily is very quiet today. B: Yes, she is. She .
Lily is very quiet today. Yes, she is. She may not be feeling well.
29.2 Complete each answer using the verb in brackets.
A: Where's Ruth? B: I'm not sure. She might be having a cigarette outside. (have)
Where's Ruth? I'm not sure. She might be having a cigarette outside.
A: Who was that woman with Craig on Saturday? B: I'm not sure. It may his cousin. (be)
Who was that woman with Craig on Saturday? I'm not sure. It may have been his cousin.
A: Has the parcel come? B: I can't see it. It may not yet. (arrive)
Has the parcel come? I can't see it. It may not have arrived yet.
A: Nisha said she'd meet us at the gate, but she isn't here. B: She might in the car park. I'll go and look. (wait)
Nisha said she'd meet us at the gate, but she isn't here. She might be waiting in the car park. I'll go and look.
A: How did Mum find out that I'd scraped the car? B: I don't know. I suppose Ellie may her. (tell)
How did Mum find out that I'd scraped the car? I don't know. I suppose Ellie may have told her.
A: Is Martin still at the cricket club? B: He was there earlier, but he might home by now. (go)
Is Martin still at the cricket club? He was there earlier, but he might have gone home by now.
A: What's Kyle doing up in his room? B: I'm not sure. He might for his exams. (revise)
What's Kyle doing up in his room? I'm not sure. He might be revising for his exams.
A: Does Cath have any children? B: I'm not sure. I think she may a son at university. (have)
Does Cath have any children? I'm not sure. I think she may have a son at university.
A: I can't find my reading glasses. Have you seen them? B: You may them at the optician's this morning. (leave)
I can't find my reading glasses. Have you seen them? You may have left them at the optician's this morning.
A: I knocked on Jordan's door, but he didn't answer. I know he was in. B: He might not you. (hear)
I knocked on Jordan's door, but he didn't answer. I know he was in. He might not have heard you.
A: Sian is supposed to meet us here, and she's half an hour late. B: She may . She's always forgetting things. (forget)
Sian is supposed to meet us here, and she's half an hour late. She may have forgotten. She's always forgetting things.
29.3 Complete the answers using might not have ... or couldn't have ...
A: I was surprised Rob didn't reply to the invitation. Perhaps he didn't get it. B: Maybe. He might not have got it.
I was surprised Rob didn't reply to the invitation. Perhaps he didn't get it. Maybe. He might not have got it.
A: I wonder why Leah went home early. Perhaps she wasn't feeling well. B: It's possible. She well.
I wonder why Leah went home early. Perhaps she wasn't feeling well. It's possible. She might not have been feeling well.
A: How did the window get broken? Was it the wind? B: No, it the wind. There's a cricket ball on the carpet.
How did the window get broken? Was it the wind? No, it couldn't have been the wind. There's a cricket ball on the carpet.
A: Saira says she looked for you at the station. B: Well, she very hard. I stood under the clock for an hour.
Saira says she looked for you at the station. Well, she couldn't have looked very hard. I stood under the clock for an hour.
A: The woman who rang you, are you sure she was from the bank? B: No, I'm not sure. She .
The woman who rang you, are you sure she was from the bank? No, I'm not sure. She might not have been.