|something is posible or allowed only for present or past (could) Present perfect - to be able to
|I can't do this. I couldn't do this. I haven't been able to do this.
|Be able to / Managed to
|capable to do stg in a special situation Although I didn't know the rules I was able to win the match.
|- past for can I could hear that noise. - for make suggestions for now and future (possibility now or in the future) We could go to the cinema - not realistic actions I could slep for a week
|Could have done
|- for the past I was so tired I could have slept whole day. - stg was possible but did not happened I could have got you a ticket (but I didn't)
|- sth not possible now I couldn't live in the City. I hate it
|- for the past I was on Holidays. It couldn't have been better.
|I can + infinitive I can't + Infinitive Can I + infinitive
|I could + infinitive I couldn't + infinitive Could + I + infinitive
|I could have been ... I could have + erd I couldn't have + erd