WORD CLASS: MODAL/AUXILIARY VERBS

1. Modals and auxiliary verbs are non-lexical verbs that bring syntactic values to the main verb. Some of them can also work like lexical verbs, for example ser (=’be’), and other do not, for example poder (=’can’). The cluster of one or more auxiliary-modal verbs is known as periphrastic conjugation. 

2. Ser + V_participle is used to express the passive voice:

la seva opinió va ser rebutjada	his/her opinion was rejected
la ciutat serà declarada patrimoni de la humanitat	the city will be declared world heritage

3. Anar + V_infinitive is used to express simple past; in this case, the auxiliary is used just in the present tense, yet it always expresses a past time:

vaig perdre la cartera al metro	I lost my wallet in the underground
us van invitar a la festa?	were you invited to the party?

4. Haver has two main uses.

a) Haver + V_participle to form compound (perfect tenses)

has vist la meva camisa blava	have you seen my blue shirt?
quan vas venir, jo encara no havia arribat	when you came, I hadn’t come yet

b) Haver de + V_infinitive to express obligation or advice (in conditional)

hauries de caminar més	you should walk more
he de fer un viatge i no en tinc ganes	I must make a trip and I don’t feel like

5. Estar + V_gerund to form continuous tenses:

estic mirant el preu d’aquests pantalons	I’m having a look at the price of these trousers
no us esteu comportant bé	you aren’t behaving properly

6. Deure+ V_infinitive to express:

ja deuen ser quarts de deu	it must already be half past nine
deuen venir d’ací a poc	they must be coming soon

7. Poder + Vi_nfinitive to express ability and also permission (including polite questions)

no puc llevar-me tan d’hora	I can’t get up so early
el meu germà no pot beure llet	my brother can’t drink milk
no pots sortir d’ací sense permís	you may not get out of here without permission
puc pagar amb la targeta?	can I pay with credit card?
em sap greu, però no es pot	sorry, but it’s not possible