一曲多語 - 服

Yes, the song is written for 李克勤 first before it is used for World Within OST. I think the Korean version is better though ....

原裝正版: 服 - 李克勤

韓文版: 연연 (姻緣) - 성시경 (成始境) (그들이 사는 세상 The World they live in OST)