The modal verbs are a class of auxiliary verbs. Modal auxiliary verbs are verbs which 'help' other verbs. Words are used with other verbs to express different functions such as obligation, ability, advice, opinion, prohibition ... and more. The following are modal auxiliary verbs:
can - could - may - should - would - must - ought to
In a Affirmation, the word order is Subject + Modal verb + Main verb
- They can come (Ellos pueden venir)
Yes o no questions:
- Can they come? (¿Pueden venir?)
- When can they come? (¿Cuándo pueden venir?)
The modal can, in spanish "poder", indicate a possibility or capacity.
- Tom can help you (Tom puede ayudarte)
- Eating out can be costly (Comer fuera puede ser costoso)
- Can I help you? (¿Puedo ayudarte?)
- Can Mike have dinner with us? (¿Mike puede cenar con nosotros?)
The modal could indicate a possibility or capacity in the past.
- I could have told you that (Podría haberte dicho eso)
- I could run very fast (yo podía correr muy rápido)
- It could rain tonight (Puede llover esta noche)
- This could be dangerous (Eso puede ser peligroso)
- Could this be a mistake? (¿Podría ser esto un error?)
- We could go see movie (Podríamos ver una pelicula)
The modal may indicate an action that can happen in the future.
- This may be a bad idea (Quizás esto sea una mala idea)
The modal must indicates obligation.
- Tom must see a doctor immediately (Tom debe ver un médico inmediatamente)
- You must be angry (Estará enojado)
- When should / must we be there? (¿Cuándo debemos estar allá?)
The modals should and ought to indicate an obligation, and both are synonymous.
- You should / ought to call your mother (Debes llamar a tu mamá)
- Should he call her? (¿Debe llamarle a ella?)
The modal would followed by the word like is a polite way of indicating a preference.
- I would like white wine with my fish (Me gustaría el vino blanco con mi pescado)
- Where would you like to eat dinner? (¿Dónde le gustaría cenar?)