How to use CAN, COULD and BE ABLE TO in English

🔸Can ► possible or allowed (or ability to do something)
can + infinitive
- I can speak three languages.
negative: can't (cannot)
- Lions can not fly.
🔸Somebody is able to do something (can is more usual)
CAN has only two forms: present (can) and past (could) ► Sometimes it is necessary to use (be)
able to.
Compare:

￭ Peter can come tomorrow	￭ Peter might be able to come tomorrow
￭ Jennifer can speak Chinese and Portuguese and Arabic.	￭ Applicants for the job must be able to speak three foreign languages.

🔸Sometimes could = the past of can
Ask for permission or request something (in the present)
- Could we go to school now?
◼ Could ►general ability. |  Use was/were able to or managed to ► somebody did something in a specific situation
- The fire spread through the house, but everyone was able to escape (or managed to escape) (could escape).