会 / 能 / 可以【huì / néng / kěyǐ】

English "can" covers three Chinese words. 会 is a skill you learned. 能 is being able to, given your body, your time or the situation. 可以 is being allowed. Each also has its own point.

会 or 能

会 answers "do you know how?". 能 answers "is it possible for you?". Someone who never learned says 不会; someone who knows how but is prevented says 不能.

• × 我不能游泳 (meaning you never learned) → 我不会游泳

能 also measures an ability: how much, how far, how fast.

可以 or 能

Both can ask and give permission. 可以 is the usual word for asking; 不能 is the usual refusal. 不可以 sounds strict, like a parent to a child.

• × 我会用你的电脑吗？ → 我可以用你的电脑吗？

可以 also offers an option: "you could".

会 has a second meaning, "will", for predictions: 明天会下雨. That one has nothing to do with skill.