Can, Could, Be Able to / (habilidad)
I can learn - I could understand - I am able to learn
Could (do), Could have (done)
I could study more - I could have studied more
Must (have), Can't (have)
You must have fallen asleep - You can't have been paying attention
Must y Can't
You have been working all day. You must be tired.
Must, mustn't, didn't need to and needn't
You must keep my secret.
May and Might (future)
He may be in the office - He might be eating lunch
Can, Could, May, Would (solicitudes, permiso, ofrecer e invitaciones)
Can you wait please? - Could you tell me the time? - Would you do me a favor?
Have to, Must
I have to clean my room - You must come with me
Had better - It's time - Should
I'd better clean up my home before my friends come over.
You should do your homework today.
Mas sobre should y sus usos.
I suggest you take a vacation - He demanded we have dinner with him
It would be nice to buy a new car but we can 't afford it.