求助Modal Verbs 中Can 、Could和Be able to的用法,和有什麼分別

Can係現在式，could係過去式，睇情況而用。如果係現在式，通常任何情形都可以用can，問問題就多數用can。

Can I please have the smoked salmon for starter and lamb for main?
Can you please spell your name?
Can I please borrow your handbook for the lecture?
I can play violin & piano.

Could係can既過去式，通常用could係因為事件已經過去，但可能未曾完成，所以會用could。

Could you please park your car on the left instead?
你可唔可以把你的車輛停在左邊？(你可能已經停了車，但被要求停在左邊)
Thank you for your application form. could you please fill in English?
多謝你的申請書，請你用英文填寫。(你已經填了，但被要求用英文填寫。)

Be able to係被動少少，應該可以，唔一定保証，但十成十無問題。

We have two cancellations for the concert tonight, we are able to fit you in.
I am please to be able to offer your the VIP seating for the football match tomorrow.

*******希望幫到你啦！*********************