Modal verbs

Modals – past possibilities, certainties and deductions

Modals – basics
Common modals include:
must, should, might, may, can, could, will, would.
Modals affect the meaning of sentences.
For example, some of them can be used to show possibility or probability.
Example: 1. I meet my boss at ten o'clock every day.(a statement of fact) I might see my boss tonight.(the modal ‘might' expresses a probability or possibility)
2. John can't see his boss tonight.(the modal 'can't' means that it is not possible for John to see his boss tonight)
Grammar note:With a present or future reference, the modal is followed by a base verb (the infinitive form of the main verb, without 'to').
I might see my boss tonight.He could be in London.She may arrive late.
Modals – possibility, probability, guesses and deductions
Modals can be used to show possibility, probability, a guess or a deduction (a guess which is based on evidence).
For example, you are in your house and the doorbell rings (you can't see who is at the door). You say:
That must be the postman.(This means you are certain it is the postman)
That might be the postman. (You are not certain, but it is possible/probable)
That may be the postman.(You are not certain, but it is possible/probable)
That could be the postman(You are not certain, but it is possible/probable)
That can't be the postman.(You are certain that it is NOT the postman)
Modals and past events
Must, might, may, could and can't are also used to talk about past probability and possibility, and to make guesses and deductions about things that happened in the past.
For example, after a shopping trip you go to the train station to return home. You can't find your wallet.
Past certainty I must have left it in the last shop. I don't remember putting it in my pocket. (This means you are certain about something that happened in the past)
I can't have left it in the last shop. I remember putting it in my pocket. (This means you are certain about something that DIDN'T happen in the past)
Past possibility/probability Someone might have stolen it.Somebody may have taken it.I could have dropped it.
Grammar note:When modals are used to talk about past events, the modal is followed by the perfect infinitive, without 'to'. The perfect infinitive is made with ‘have' + the past participle of the main verb. Here are some examples of modal verbs followed by perfect infinitives:
must have leftmight have stolenmay have takencould have dropped
Remember, if you don't use a modal, then you are giving a fact, for example: I left it in the shop.
Be careful: Modal verbs often have other different meanings. For example, 'could' can be used to show ability as well as possibility. Use the context to help you understand which meaning is being used. 'Can' is NOT normally used to talk


EXERCISES ON MODALS:


Modal Final Test
Multiple Choice Exercise
Your score is 72%.Some of your answers are incorrect. Incorrect answers have been left in place for you to change.
1. Ted's flight from Amsterdam took more than 11 hours. He must be exhausted after such a long flight.
2. The book is optional. My professor said we could read it if we needed extra credit. But we don't have to read it if we don't want to.
3. Susan couldn't hear the speaker because the crowd was cheering so loudly.
4. The television isn't working. It must have been damaged during the move.
5. Kate: Can you hold your breath for more than a minute?Jack: No, I can't.
6. You don't have to be rich to be a success. Some of the most successful people I know haven't got a penny to their name.
7. I've redone this math problem at least twenty times, but my answer is wrong according to the answer key. The answer in the book must be wrong!
8. You couldn't do the job if you didn't speak Japanese fluently.
9. You shouldn't worry so much. It doesn't do you any good. Either you get the job, or you don't. If you don't, just apply for another one. Eventually, you will find work.
10. You should be kidding! That can't be true.
11. You would leave the table once you have finished your meal and politely excused yourself.
12. Jenny's engagement ring is enormous! It must be costing a fortune.
13. Shall we move into the living room? It's more comfortable in there and there's a beautiful view of the lake.
14. If I had gone white water rafting with my friends, I would have float down the Colorado River right now.
15. At first, my boss didn't want to hire Sam. But, because I had previously worked with Sam, I told my boss that he ought to take another look at his resume and reconsider him for the position.
16. You can take along some cash. The restaurant may not accept credit cards.
17. The machine can be turned on by flipping this switch.
18. I can't stand these people - I have got to get out of here. I'm going to take off for awhile while you get rid of them.
19. You mustn't forget to pay the rent tomorrow. The landlord is very strict about paying on time.
20. Do you always have to say the first thing that pops into your head. Can't you think once in a while before you speak?
21. Terry and Frank said they would come over right after work, so they can to be here by 6:00.
22. Yesterday, I had to cram all day for my French final. I didn't get to sleep until after midnight.
23. We shall no longer suffer the injustice of oppression! Freedom shall be ours!
24. If I had gone to the University of Miami, I could have participated in their Spanish immersion program.

Source: http://www.englishpage.com/modals/interactivemodal8.htm