TThey are INCOMPLETE VERBS. ›T›They don’t have all the tenses. ›T›There is not past participle, so there is not passive. ›T›They use other verbs to complete the tenses. - CAN is completed with BE ABLE TO “They can play the piano.” “They will be able to play the piano in the future.” - MUST is completed with HAVE TO “You must come early.” “You had to come early yesterday.”

TThey don’t have –s in third person singular of the present simple “ He can open the door” “ She must come early”

TThey are followed by an infinitive without 'to' in most cases. BUT: NEED takes 'to' when expressing absence of obligation in the negative: You do not need to stay if you don't want to. OUGHT TO i s a special case and you must learn it like that. It expresses convenience. Ex: You ought to study more more if you want to pass the exam.

TThey don’t need auxiliary verb in the interrogative or negative form “ Can I help you?” “ We shouldn’t go to the toilet”

PROBABILITY/POSSIBILITYABILITYPERMISSIONOBLIGATION/ADVICEOFFERSCAN I can play the piano Can I go out tonight? CAN’T She can’t be his mum. She ‘s too young I can’t speak German Can I borrow the car? No, I can’t. MIGHT It might rain tomorrow MAY NOT MIGHT NOT If the bus doesn’t arrive soon, we may not see the start of the film COULD It could rin tomorrow I could already read when I was two Could I see your passport please, sir? MAY It may rain tomoroww May I leave the table? MUST She must be his sister because they look alike. You must leave before the clock strikes twelve. HAVE TO I have to study tonight. SHOULD / OUGHT TO You should see it. It’s excellent. HAD BETTER You had better sleep more. WOULD Would you like a drink?

SSon modales que se refieren siempre a acciones ocurridas en el pasado. FFORMACIÓN: MODAL + HAVE + PARTICIPIO PASADO Ejemplos: It must have been a difficult decision They should have invited her to their wedding

MODAL PERFECT USESEXAMPLES MUST HAVE + P.P. Conclusión lógica sobre un hecho del pasado Linda has arrived late. She must have been in a traffic jam MAY / MIGHT HAVE + P.P. Una suposición sobre algo pasado She may / might have taken the wrong bus. COULD HAVE + P.P. Habilidad de haber hecho algo pero finalmente no lo hizo You could have asked the doctor before taking that medicine COULDN’T HAVE + P.P. Certeza de que algo no pudo haber sucedido He couldn’t have gone to the concert because he was doing a test WOULD HAVE + P.P. Quiso haber hecho algo, pero no pudo hacerlo por causas externas I would have gone to the party, but I was too busy SHOULD / OUHT TO HAVE + P.P. Queja de que algo haya ocurrido en el pasado o lamento de que no se haya cumplido lo que esperábamos You should / ought to have warned me earlier SHOULDN’T HAVE + P.P. Crítica sobre un acontecimiento pasado que no debería haber ocurrido He shouldn’t have forgotten about her birthday NEEDN’T HAVE + P.P. No había necesidad de hacer lo que se hizo en el pasado You needn’t have brought anything to my party.