Permission (giving/not giving permission, asking for permission)
You may leave now; You may not leave now; May I leave now?
You can smoke if you want to; You can’t smoke in here; Can I smoke?
You are allowed to smoke in this room; You aren’t allowed to smoke; May I smoke?
Offering help (asking to do something for 2nd persons)
Shall I carry that (for you)? (¿Te llevo eso?)
Shall we call an ambulance? (¿Llamamos a …?)
Note: (only questions; subject: 1st persons: I, we; translated in the present)
Una frase suelta: Can I help you?
Asking for help (asking a 2nd p. to do something for you)
Will you help us with these parcels? (¿Nos ayudáis …?)
Will you go & get some chalk, please? (¿Me vas por…?)
Note: (only questions; subject: 2nd persons: you; translated in the present)