MODAL VERBS. THEORY

MODAL VERBS

DEDUCTIONS AND POSSIBILITIES

• Para expresar conclusiones probables de las que estamos seguros o casi seguros:

- En el presente:

* Must + infinitivo (en frases afirmativas): She isn’t at home. She must be at work.

* Can’t + infinitive (frases negativas): She can’t like dancing. She hardly ever dances.

- En el pasado:

* Must / can’t + have + participio : he said he would phone me but he didn’t. He must have forgotten.

- Conclusiones que se refieren al momento en el que estamos hablando:

* Must + be + gerundio: he’s very quiet. He must be thinking about something.

• Si no estamos muy seguros de nuestras conclusiones:

* Might / may / could + infinitivo (frases afirmativas): I wonder where my mobile is. It may be in the car.

* Might / may not + infinitivo (frases negativas): she is not here yet. She may not come.

ADVICE, SUGGESTIONS AND OPINIONS

• En el presente: should / ought to /would rather / had better + infinitive.

You should phone your parents. They seem to be worried.

I would rather go to the cinema than go to dance.

Hadn’t you better go? It’s nearly midnight.

‘Had better’ se suele usar en forma negativa en preguntas y ‘ought to’ no se suele usar en preguntas.

• En el pasado: should / ought to + have + participio. En pasado estos verbos expresan expectativas que no llegaron a cumplirse o críticas por algo que sucedió.

She should have got the post.  / He shouldn’t have got so angry.

They ought to have waited for her. ‘ought to have’ no es frecuente en frases negativas.

OBLIGATION AND NECESSITY

• Para expresar necesidad utilizamos ‘need to’: we need to buy some batteries for the camera.

• Para obligación: must /have to+ infinitive. We have to be here at five.

• En pasado: ‘had to’ + infinitive. I had to cancel my holidays last year.

LACK OF OBLIGATION OR NECESSITY

• Presente:

- Don’t have to: these are extra exercises. You don’t have to do them if you don’t want to.

- Needn’t: you needn’t give me back my camera until next week.

• Pasado: didn’t have to / didn’t need to. Para decir que algo se hizo y no era necesario usamos ‘needn’t + have + participio.

I needn’t have bought the newspaper; my wife had already bought one.

PERMISSION

• En el presente, futuro  o en general: can / could / may.  You can come a bit later.

‘Could’ and ‘may’ en preguntas se utiliza en contextos más formales. Could you help me? May I ask you a question?

• En pasado: could, was/ were allowed to: when we were children, we were allowed to sleep at our friends’ houses at weekends.

ABILITY

• Para expresar una habilidad en el presente:  ‘can’. I can play the guitar.

• Para expresar una habilidad en el pasado:

- Could: habilidades generales. When I was five I could read.

- Was /were able to: expresa una habilidad en una ocasión concreta del pasado.

Tom was able to persuade his parents to buy him a bike for passing his exams.

• Para expresar una habilidad en el futuro:

When I finish high school I will be able to fulfill my dream: study medicine.

‘Be able to’ puede utilizarse en cualquier tiempo verbal y es la única opción cuando no podemos utilizar ‘can’ o ‘could’.

I’ve been able to fix the TV (he podido arreglar la tele).