如何理解it's only fair

如何理解it's only fair it`s only the fair tale 伴奏 it‘s not fair it's not.fair it's only the fair tale是哪个动漫 "Excuse me,sir,but I think it's only fair to tell you that i And now it's only fair that I should let you know fair‘s fair it’s not for you.如何理解 fair's it isn't fair和it's not fair的区别 it's the only