replace the old with the new; change the new for the old; denounce the old and hail the new; prefer new to old acquaintances; throw sb. over for a new acquaintance; turn back on sb. (lover, etc.) and go with another
If sandy's music got to be too burdensome, some time, i would let a knight defeat me, on the chance that she would desert to him . 桑弟的音乐要是有一天太让人受不了的话，我就不妨叫一位骑士来把我给打败了；那么一来，她也许就会弃旧迎新了吧。
