Modal Verbs of Possibility: may, might, could

The word “possibility” means that something is possible. Possibility is expressed by the modal verbs may, might, could. The speaker thinks that something is possible, but doesn’t know for sure and implies “maybe, perhaps”. Let’s revise modal verbs of possibility.

Exam in Mind Level B1/B2

May, might, could are used to express a weak degree of certainty (less than 50% certainty).

  • Where is Mike? He may be in the garden. He might be in the attic. He could be in the garage.
  • Why didn’t he go to the party yesterday? He may have been busy. He might have been sick. He could have been too tired to go to the party.

The modal verbs may, might, could are very close synonyms in the meaning “possibility”, though may expresses a bit stronger possibility than might or could.

The main meaning of might is “possibility”. May and could can express several meanings. The context, as usual, is the most reliable means of recognizing the meaning of modal verbs in this or that situation:

  • May I leave now? (request for permission)
  • You may leave now. (permission)
  • He may leave for Rome soon. (possibility)
  • He may leave. (permission or possibility?)

Quite often, the use of the infinitive be after the modal verbs may, might, could is an indication that the meaning is “possibility”. Also, the perfect infinitive of the main verb after these modal verbs usually signals that the meaning is “possibility”.

  • You may be right.
  • They might be at home.
  • He may have left already. 
  • He could have been sleeping when I called him.


The verb might may be used in polite requests for permission in the same way as may, but such use of might is very formal. Compare: May I come in? (polite)  Might I come in? (very formal, very polite)

The modal verbs may, might, could in the meaning “possibility” form two tenses: the present and the past. The future is expressed by the present tense forms. Additionally, adverbs and adverbial phrases indicating the future time can be used (e.g., tomorrow, soon, next week).

May, might, could in the meaning “possibility” express the present (may help; might know; could be) or the past (may have helped; might have known; could have been) depending on the infinitive form of the main verb with which the modal verb is used.

The present tense is formed by combining may, might, could with one of the infinitive forms for the present tense: with the simple infinitive, the continuous infinitive, or the passive infinitive. The simple infinitive (active infinitive) is used more frequently.

With simple / active infinitive:

  • She may be at home now.
  • He may leave for Rome soon.
  • He may not know my address.
  • It may rain in the evening.
  • He might be at the library.
  • She might ask him for help.
  • It might be difficult to do.
  • He might go there tomorrow.
  • He might not come back soon.
  • I don’t know where he could be.He could be at school or at home.
  • It could be John, but I can’t see clearly.

With continuous infinitive:

  • They may be working now.
  • He might be sleeping now.
  • He could be sleeping now.
  • He could be playing tennis at the club at the moment.

With passive infinitive:

  • This work may be done tomorrow.
  • She might be offered a new job.

With perfect infinitive:

  • He may have been at home then.
  • She may have left already.
  • She may not have known his address.
  • He might have been at the bank.
  • He might not have come back yet.
  • He might have told her the truth.
  • I really don’t know where he could have been last week.
  • It could have been John, but I’m not sure.

With perfect continuous infinitive:

  • She may have been walking her dog yesterday in the evening.
  • They might have been sleeping when she called them in the morning.
  • He could have been playing tennis at the club at that time.

With perfect passive infinitive:

  • It might have been done already.
  • He may have been offered a new job.

May and Might in the Past Tense

In certain cases might is used as the past form of may, for example, in reported speech according to the rules of the sequence of tenses:

  • He said, “I may go there soon.” – He said that he might go there soon.
  • She said, “I may have dropped my keys in the park.” – She said that she might have dropped her keys in the park.

May and Might in Conditional Sentences

Both may and might are used to express possibility in sentences with real condition:

  • If he repairs his car, he may go to the lake with them tomorrow. (real condition referring to the future)
  • If he repairs his car, he might go to the lake with them tomorrow. (real condition referring to the future)

Only might is used in conditional sentences with unreal condition:

  • If he repaired his car, he might go to the lake with them tomorrow. (unreal condition referring to the present or future)
  • If he had repaired his car, he might have gone to the lake with them yesterday. (unreal condition referring to the past)

Note: could is also used in conditional sentences with unreal condition:

  • If Jack had come here, I could have given him this book.
  • I could have helped you if you had asked me earlier.
  • If I were at the fair, I could have bought the book for you.
  • Had you participated in the contest, you could have won the first prize.
  • Had John come to the office, he could have done the task.

May, Might, Could in Questions

Usually, may and might in the meaning “possibility” are not used in questions. The substitute phrases “be likely; Is it possible; Are you sure” replace them in questions:

  • Is he likely to return soon? 
  • Is she likely to be at home now? 
  • Was he likely to tell Mike about it? 
  • Is it possible that she is at home now? 
  • Are you sure that he told Mike about it?

To avoid misunderstanding or mistakes, ask questions using the phrases “be likely; Is it possible; Are you sure” instead of may, might, could or ask questions without the meaning “possibility”. For example:

  • She may know him. – Is she likely to know him? Is it possible that she knows him? Are you sure that she knows him? Does she know him?
  • He might be there now. – Is he likely to be there now? Where is he now? Where can I find him? Is he likely to return soon? Is she likely to be at home now? Was he likely to tell Mike about it? Is it possible that she is at home now? Are you sure that he told Mike about it?

Could in the meaning “possibility” is used mostly in general questions, but special questions are also possible:

  • Could it be true?
  • What could it be?
  • Could he be lying to us about his past?
  • Could she have said such a thing?
  • Could he have written this letter? 

Sufficient context is needed to distinguish the meaning “possibility” from the other meanings of could. Compare:

  • Could you write a letter to her? (request)
  • Could he write in English when he was 15? (ability; here could is the past form of can)

May, Might, Could in Negative Statements

May and might are used in negative statements in the meaning that there is some possibility that some action might not take place:

  • He may not be home yet.
  • They may not have seen my letter.
  • It might not be true.
  • She might not know his address.
  • I might not have locked the door.

Couldn’t (and can’t) indicate that the speaker strongly believes that something is really impossible (improbable):

  • It couldn’t be true! / It can’t be true!
  • It couldn’t have been true! / It can’t have been true!
  • He couldn’t be lying to us. He is an honest man.
  • He couldn’t have taken the money! / He can’t have taken the money!
  • It couldn’t have been Tom. Tom was in Chicago last week.

May and Might with Have to and Be Able to

May and might are used in combinations with have to and be able to:

  • He may have to move to another city soon. (Возможно, ему придётся переехать в другой город скоро.)
  • We may have to tell him about it.(Возможно, нам придётся сказать ему об этом.)
  • She might have to sell her apartment. (Возможно, ей придётся продать свою квартиру.)
  • They might have to pay a fine. (Возможно, им придётся заплатить штраф.)
  • She may be able to help us. (Возможно, она сможет помочь нам.)
  • He might be able to help you. (Возможно, он сможет помочь вам.)
  • They might not be able to come to the party tomorrow. (Возможно, они не смогут прийти на вечеринку завтра.)
  • He might have been able to solve this problem. (Возможно, он смог решить эту проблему.)

Substitutes of Modal Verbs of Possibility

The adverbs maybe, perhaps and the phrase It is possible that are simple and useful substitutes for the modal verbs of possibility:

  • Maybe he’s still at home.
  • Maybe he was sick yesterday.
  • Maybe he will tell us about it.
  • Maybe she didn’t go there.
  • Perhaps he’ll come back.
  • Perhaps she is still at home.
  • Perhaps he was right.
  • It’s possible that she doesn’t know them.
  • It’s possible that he’ll come back on Friday.

Have practice in using modal verbs of possibility

Task 1. Choose the most appropriate answer to express possibility that is NOT very strong.

1. He ______ able to help you.

a. may
b. must
c. should
d. will

2. She ______ have to sell her car and other belongings to pay her debts.

a. will
b. will probably
c. might
d. would

3. Where is Anna? – I don’t know. She ______ be at the swimming pool or in the park.

a. could
b. should
c. must
d. has to

4. It ______ be as easy as you think.

a. can’t
b. couldn’t
c. might not
d. must not

5. Don’t ring the doorbell when you get there. Maria’s little baby ______ sleeping.

a. must be
b. should be
c. may be
d. may not be

6. How did the robbers get in? – We don’t know yet. The old woman ______ to lock the door.

a. might forget
b. could forget
c. might have forgotten
d. must have forgotten

7. I called her but there was no answer. She ______ left for New York already.

a. may have
b. must have
c. should have
d. has probably

8. When can I see him? ______ come back before six today?

a. May he
b. Might he
c. Would he
d. Is he likely to

9. I wonder who wrote that letter. ______ Jim have writeen it?

a. May
b. Might
c. Could
d. Is it possible that

10. He said that he ______ go to Italy in June or July.

a. can
b. should
c. might
d. would

Use modal verbs of possibility in the sentences of your own.