teach an old dog new tricks 教老狗新把戏；教老狗学新招

【例句】
My father will never change：you can't teach an old dog new tricks.
我爸爸永远不会改变，真是老狗学不会新花样。

Yet some people say that you can never teach an old dog new tricks.
但是有人说你永远不能教老狗新把戏。