The document discusses modal auxiliary verbs in English. It provides examples of how modal verbs are used and the rules that govern them, such as always being followed by an infinitive verb and having no past tense forms. Specific modal verbs like can, could, must, should, have to are explained in terms of their meanings and uses for ability, permission, obligation, advice and other functions. An exercise is provided asking to complete sentences using the various modal verbs.

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.
COULD
 Could (/kʊd/, /kəd/) is used for past ability:
o When I was 7 I could read and write very well.
 Could is used when asking permission:
o Could I borrow your red pen?
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.
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.
EXERCISE: Complete with can, can’t, could, couldn’t, should, shouldn’t, must, mustn’t, have/has to,
don’t/doesn’t have to:
1. Do you think I _________________ wear those old trousers or these new ones?
2. Helen is busy until lunch time, but she ____________________ meet us for lunch.
3. I am studying. I __________________ talk right now.
4. In the 1960s people ____________________ send letters by post but they ______________ send
emails. Now we ____________________ send emails or use social networks.
5. In this school you __________________ wear a uniform.
6. Many Australians grow up near the sea. They ___________________ surf when they are children.
7. You ____________________ be late. If you are the teacher won’t let you take the exam.
8. You are sensitive and intelligent. I think you ___________________ study medicine.