Grammar for ESO-4

1. English Department
Modal verbs CPI Tino Grandío
MODAL AUXILIARY VERBS
 They are always followed by another verb in the infinitive without to.
o You shouldn't smoke.
 They have no -(e)s on the third person singular.
o He can't swim.
 Questions and negatives are made without do.
o If I were you I wouldn't do that.
 Modal verbs have no infinitives; other expressions have to be used instead, when an infinitive is necessary.
o I want to be able to swim. (Not: *I want to can swim.)
o I had to visit her yesterday. (Not: *I must visit her yesterday.)
 Modal verbs have no past forms (could and would are sometimes used with a past meaning).
CAN (BE ABLE TO)
 We use can (/kæn/, /kən/) when we want to say that something is possible or somebody has the ability to do
something.
o You can dance very well.
 Can may be used for suggestions:
o We can go to the new swimming pool in the afternoon.
 Be able to is used when an infinitive (or another tense) is needed:
o They will be able to speak French next year. (Not: *They will can speak French next year.)
o We haven’t been able to finish on time.
 In the negative can't (/kɑ:nt/) is used:
o We can't speak German well.
 Can't is used when we realize that something is impossible:
o It can't be true.
COULD
 Could (/kʊd/, /kəd/) is used for past ability:
o When I was 7 I could read and write very well.
 It is also used for deduction, when we think that something is possible:
o They could be right about that.
 Could is used when asking permission:
o Could I borrow your red pen?
MAY / MIGHT
 May (/meɪ/) is used when asking permission (it's more formal than could):
o May I go to the toilet? Yes, of course.
 We use may or might to say that something is possible:
o It may / could / might rain this afternoon.
MUST
 Must (/mʌst/) is used when we know that something is necessary:
o You must study harder, otherwise you'll fail.
 In the negative it means negative obligation:
o You mustn't lose my key. It's the only one I have.
 Must is also used when we are certain about something:
o They aren't answering the phone. They must be out.
SHOULD / SHOULDN'T
 Should and shouldn't are used for giving advice:
o You should lose some weight if you want to be healthy.
o We shouldn't wait any longer.
HAVE TO / DON'T HAVE TO
 Have to is not really a modal verb as it doesn't share all their characteristics.
 Have to is used to provide all the tenses that must doesn't have:
o He will have to come with me tomorrow.
 In the negative don't/doesn't have to means lack of obligation (≠ mustn't)
 You don't have to finish the exercises today. You can do them at the weekend.
NEED / NEEDN’T
 Need to, just as have to does, expresses obligation. It can be used in all the tenses.
o I need to finish it now. They can’t wait.
 In the negative you can use don’t/doesn’t need to, or the more formal needn’t + bare infinitive:
o You don’t need to help me. / You needn’t help me.
PROBABILITY
- MUST 100%
- MAY 50%
- MIGHT 30%
- COULD 30%
- CAN'T 0%

2. EXERCISE:
1. I'm hungry. I think I ______________ have a sandwich.
2. You have been working very hard. I think you ______________ have a break.
3. You ______________ be patient. You can't always get things immediately.
4. ______________ go to the toilet?
5. We have run out of milk. You ______________ go to the supermarket and buy two cartons.
6. I'm not sure. I ______________ pass this exam.
7. ______________ you swim? Yes, but not very well.
8. ______________ you turn off the radio? I can't speak to your brother.
9. Rebecca is very intelligent. She ______________ speak five languages.
10. I forgot to phone my mother last night so I ______________ phone her today.
11. Isn't this classroom too hot? I ________________ open the window.
12. You ______________ speak to your mother like that. She will be very upset.
13. We ______________ ride a bike but we ______________ ski.
14. If I am not better I ______________ not go to work tomorrow.
15. Look at my shoes! They are so dirty. I ______________ clean them now.
16. Last night I was very tired but I ______________ sleep.
17. Your father ______________ smoke so much if he wants to get better soon.
18. Some of his friends ______________ go to the school trip because they had flu.
19. It ______________ be your sister. (= I'm sure it is your sister.)
20. Have you seen my keys? I ______________ find them.
21. (She doesn't know yet) My cousin ______________ come to the party.
22. ______________ I smoke here?
23. I wasn't hungry yesterday evening so I ______________ finish my dinner.
24. This is an excellent film. You ______________ watch it. I'm sure you'll love it as much as I did.
25. I'm sorry but I ______________ go to your birthday party next week.
26. Take an umbrella. It ______________ rain.
27. I don't think you ______________ spend so much money on clothes.