Would, Will, Could, Can 英文的用法和差異

Will 是未來式:I will never cheat on you. Would 是過去的未來式: He said that he would never cheat on you. 然而,would 還帶有假設語氣的用法:if I were him, I would never cheat on you. 除了 if,用在表達想法的句子裡也應該使用假設語氣:I think the meal would be enough for ten people.

Can 是能夠的意思: I can run for miles. Could 則是過去式:When I was younger, I could run for miles. 然而,could 也帶有假設語氣的用法:If I were young, I could run for miles. 除了 if,用在表達想法的句子裡也應使用假設語氣: I think the meal could feed ten people.


could 較 would 多了一個「可能性」的意思: We could have as many as ten people for dinner tonight. 意思是「我們可能會有十個客人」,若這邊使用 can: We can have as many as ten people for dinner tonight. 意思會變成「我們有能力招待十個客人」

Would 和 Could 都有禮貌的用法:Could I borrow your car? Would you mind if I borrow your car?

Ref. http://learnersdictionary.com/qa/could-can-and-would