old habits die hard 旧习难改；积习难改；本性难移；江山易改本性难移

【例句】
Tom has been a chain smoker for years. You know, old habits die hard.
汤姆是个多年的老烟鬼了。哎，旧习难改呀。

While it is widely accepted that an effective process is important today, old habits die hard.
当今天人们已广泛接受搞笑过程是重要的这一观点的时候，旧有习惯依然难以改变。