Modal verbs:

• DEFINICION: Modal verbs are different then any other verb.they have a serie of special characteristics; .they may express necessity, prohibition, ability, obligation, lack of obligation, possibility, etc
  
• CHARACTERISTICS:
  • They lack  infinitive, participle and most verbal tenses; they need to use verbal periphrasis to complete time and tense
  • They don not take -s in teh 3rd person singular in the present simple tense. (but HAVE TO)
  • All of them are followed by an infinitive without to, but OUGHT TO, HAVE TO y NEED TO.
  • As they do not need any auxiliary verb to form the negative and the interrogative form, they use the subject- verb inversion and not  to form the negative form.CANNOT is special: can not is American English.

• MODAL VERBS
  

  	VERB	USE	EXAMPLES	NOTES
  PURE MODALS	CAN (presente)	-express ability	- We can drive very well	- Be able to complements  can when it shows ability and possibiblity : infinitive, future, present perfect y gerund, e.g. I will be able to play the guitar in a year.
  		- express possibility or impossibility	- I can't talk, I've got a very sore throat
  		- Express or ask for permission	- Can I sit down?
  		-in the negative form, express logical deduction or prohibition	- She can't be at school. It's holiday. - You cannot smoke here.
  	COULD (pasado)	- Express ability in the past	- Jane could drive before she was 18.
  		- Ask for something politely	- Could you pass the salt, please?
  		- Express possibility  o impossibility in the past.	- It was so hot I couldn't walk in the sand.
  		- Infer things (remote possibility)	- This passport could be his.
  		- Make suggestions	- We could play bingo today.
  		- replace can in the reported speech	- They said they could do it themselves.
  		- Express criticism.	- You could have bought some more food.
  	MAY (PRE/FUT)	- Ask for something	- May I leave the classroom?	- Cuando MAY indica posibilidad indica que algo no es seguro. (quizá, tal vez, puede que)
  		- give permission	- You may go to the toilet.
  		- Express present or future possibility	- The headmaster may visit the class today.
  		- speculate	- That may be the thief that was arrested by the police.
  	MIGHT	- Express  possibility (more remote<9 b="">	- They might invite us to the party.	-possibility is very remote (pudiera ser que)
  		- speculate	- They might have broken the window…
  	SHOULD	- give advice	- You should do more physical exercise
  		- Express moral obligation because something is not as we thought it should be	- You should be more tolerant
  		- Critiise past actions	- She should have been quiet
  	WILL	- Make an offer	- I'll carry the suitcase for you.
  		- Ask something politely	- Will you bring me a coffee, please?
  	SHALL	- make an offer	- Shall I open the window?
  		- make suggestions	- What shall we do tonight?
  		- make up yu rmind about taking a course of action	- I shall speak to the headmaster
  	WOULD	- make an offer  in a more polite way)	- Would you like some tea?
  		- Past habits (solía)	- When I was a child, I would go fishing.
  	MUST (presente)	- express obligation	- You must go to school	- HAVE TO completesa MUST in tenses, e.g. She had to get up early yesterday.
  		- express prohibition (negative form)	- You mustn't smoke in hospitals
  		- Express logical deduction (affirmative)	- They must be happy. They've won the lottery
  	NEED	- Express necessity	- Need we go now?
  		- Passive meaning	- The trees need pruning.
  		- In negative lack of obligation= don't have to	- You needn't get up early at weekends
  	OUGHT TO	- give advice	- You ought to do more physical exercise
  		- Express moral obligation	- You ought to be more tolerant
  	USED TO	- Express routines or habits in the past	- I used to play tennis, but now I play basket
  MODALS IDIOMS	HAVE (GOT) TO	- Express obligation (softer, lighter than must))	- You have to be 18 to drive a car
  		- in negative absence of obligation	- You don't have to wear a uniform in this school
  	HAD BETTER	- give advice or make suggestions (sería mejor)	- It's getting dark, we'd better go home now
  	WOULD RATHER	- + infinitivo: preferir algo 2 sujetos iguales - + Oración en pasado simple: (preferiría) sujetos diferentes - + infinitivo + than + infinitivo	- I'd rather stay at home (prefiero) - I'd rather she studied harder - I'd rather listen to music than dance
  	BE USED TO + -ING	- It means "estar acostumbrado a.."	- I'm used to going to bed late.
  	GET USED TO + -ING	- It means " acostumbrarse a.."	- I can't get used to his way of cooking.

  
  
• MODALES PERFECTOS:
  Whenever we use a modal perfect, we are talkin gabout the past. they are followed by HAVE+ PARTICIPLE.
  • MUST + HAVE + PARTICIPIO → PAST LOGICAL INFERENCE e.g. Sheila was absent yesterday. She must have been ill.
  • COULD + HAVE + PARTICIPIO
    → indica que hubo posibilidad de hacer algo en el pasado pero realmente no se hizo, e.g. He could have helped us, but he came too late.
    → en negativa, expresa la incredulidad de que lo ocurrido sea cierto, e.g. She couldn't have said those words.
    → para hacer una suposición en el pasado, e.g. She didn't come to the party. She could have been ill.
  • MAY / MIGHT + HAVE + PARTICIPIO → expresan una suposición sobre el pasado, e.g. Call her again. She may / might not have heard you the first time.
  • SHOULD / OUGHT TO + HAVE + PARTICIPIO
    → para lamentar que no se siguió un consejo en el pasado, e.g. She looks worse. She should / ought to have seen a doctor last week.
    → para lamentar que no se haya cumplido lo que esperábamos, e.g. They should have been home by now.
    → en negativa demuestran nuestra opinión crítica sobre algo que no debería haber ocurrido, e.g. I'm very angry with her. She shouldn't have been so rude.
    
    
    Now it's time for practice:
    - Miscellaneous