A3. Ability: We use 'can' to talk about someone’s skill or general abilities. (e.g. She can speak several languages.)
a. We use 'can' to talk about the ability to do something at a given time in the present or future. (e.g. You can make a lot of money if you are lucky. Help. I can’t breathe. They can run but they can’t hide.)
b. use 'could' to talk about past time. (e.g. She could speak several languages. They couldn’t dance very well.)
c. use 'could have' to say that someone had the ability/opportunity to do something, but did not do it. (e.g. She could have learned Swahili, but she didn’t have time. I could have danced all night (but didn't).)
Idiom 365
Go The Extra Mile: to do or make more effort than is expected
Example: We always provide and go the extra mile to make sure our customers are satisfied.