Possibility: could, may, might

We can use ‘ may’, ‘might’ or ‘could’ to say that something is possible now or later: Your bag may/ might/ could be in the car. (not It can be in the car.) We use ‘may’, ‘might’ or ‘could’ plus the perfect infinitive to say it is possible that something happened before now. I may/might/ could have lost my key.

In the negative, we can say: It may not/ might not happen. (It couldn't happen) = Можливо цього не трапиться. ‘Couldn’t’ is used to express logical assumption. It couldn’t have happened. = Навряд чи, щоб це трапилось. The interrogative is normally expressed by ‘Could?’: Peter is late. Could he be stuck in traffic? (not Can/may he be stuck in traffic?)

The form of the infinitive depends on the time reference of the action which it expresses. Study the examples:

present infinitive	Perhaps she is a nurse. It's possible he’ll come soon	She may be a nurse. He might come soon.
present continuous infinitive	Perhaps they’re having a break. It's likely we will be moving house soon.	They could be having a break. We may be moving house soon.
perfect infinitive	It's possible he left later. Perhaps she has not locked the door. It's likely he had gone out.	He could have left later. She might not have locked the door. He may have gone out.
perfect continuous infinitive	Maybe they were sleeping Perhaps it has been raining.	They might have been sleeping. It could have been raining

Ex.3 Complete the sentences using could/ may/ might:

E.g.: Maybe they are at work. – They may/might/could be at work.

Maybe they are not at work. – They may/might not be at work.

1. Maybe they're right. 2. Maybe it's just a big misunderstanding. 3. Perhaps he is waiting outside. 4. Perhaps he doesn’t know about the meeting. 5. Maybe she will work late tonight. 6. It's likely he was driving too fast. 7. It's possible they made a mistake. 8. Perhaps he hasn’t caught the bus. 9. It's possible she has been playing in the snow. 10. It's likely we will be leaving tomorrow. 11. Maybe he will stay there. 12. Perhaps she had been trying to call you. 13. It's likely they had seen the film already. 14. Maybe this wasn't such a good idea. 15. It's possible he is studying in the library.

Ex 4 Fill in the gaps with ‘may’, ‘might’ or ‘could’

I wonder why Alan didn't buy me anything for my birthday. I suppose he …………. (forget). Or he …………. (think) that now as I'm getting on, I don't like to be reminded of my advancing years. On the other hand, he ……….. (not forget)! He ……… (give) me a present this evening when I see him. Oh no! He ………….. (plan) a surprise party, as he did last year. What a disaster that was! I hope he isn't doing it again!

Ex 5 Use the perfect infinitive of the verbs in brackets with an appropriate modal verb: must, can’t, may, might, could, need, should,and was.

1. You …………… (warn) him that the ice was dangerous, (but you didn't)

2. You ………………….................… (not/ buy) bread. (It was not necessary).

3. To someone who wasn’t at the party: We had a wonderful time; you (be) there

4. (It is possible) Shakespeare …...... (write) it. – Shakespeare......… (not/ write) it because events are mentioned that didn't occur till after Shakespeare's time.

5. I can't think why they didn't try to help him. – (It is possible) They …………. (not realize) that he was drowning.

6. I found this baby bird at the foot of a tree. It ………......… (fall) from a nest.

7. You …............ (leave) a note. (It was very inconsiderate of you not to do so.)

8. The lecturer was a tall thin man with white hair. — Then it ……. (not be) Dr Fell because he is short and fat. It ……........... (be) Dr Jones; I think he is thin.

9. You...….. (not go) out yesterday without a coat. No wonder you caught cold.

10. You ….. (not/ send) a telegram. (It wasn’t necessary); a letter would’ve done.

11. They …………… (be) married next week but now they have quarreled and the wedding has been cancelled.

12. People were waiting but the bus didn't stop. ~ (It is possible) It ….... (be) full.

13. Look, there's a tree right across the road! - So there is. It ………. (be) blown down by the gale last night.

14. This building ……………… (be) finished by the end of last year (this was the plan), but there have been so many strikes that it isn't finished yet.

15. You ……………. (cross) the road by the subway. (But you didn't.)

16. I suppose it was Charles who left the kitchen in such a mess. ~ No, it …….. (not be) Charles. He never has a meal in. It …………….. (be) Bill.

17. I know she was in because I heard her radio, but she didn't open the door. ~ (Possibly) She ……………….. (not hear) the bell.

18. He……… (check) that his brakes were working properly. (but he didn't)