It is: You can't teach an old dog new tricks.

You can't teach an old dog new tricks表面意思是“老狗学不了新把戏”，其实就是指积习难改，固守陈规的人很难接受新鲜事物。

youdao

Teach an endangered species not to eat the very thing that kills it and made it endangered?

教一个珍稀物种不去捕食会使它们灭绝的食物？

youdao

While the brain's plasticity begins to degrade in later life, it may never be too late to teach an old brain new tricks.

因为大脑的可塑性在生命晚期开始退化，所以什么时候教一个老人新技巧都不显得太晚。

youdao

Yet,some people say that you can never teach an old dog new tricks.

VOA: special.2010.05.30

And again, you don't teach an animal to play Ping-Pong by waiting for it to play Ping-Pong and then rewarding it.

同样，你并不能通过等待动物打乒乓球,然后给其奖励,来使动物学会打乒乓球。

耶鲁公开课 - 心理学导论课程节选

In other words, the teaching fellows I had in those days who knows? They may rise up against me in the same way this semester -but the teaching fellows I had in those days said, "You can't teach an introduction.

也就是说，当时我教的那些学生,谁知道呢？，这学期他们也有可能以同样的方式反驳我,当时我教的那些学生说，“你不能教入门。

耶鲁公开课 - 文学理论导论课程节选

And you get RBDS station and track info, which is a nice new trick to teach an old dog.

ENGADGET: Zune review

You could teach an MBA course just on this.

FORBES: David Bach on How to Build a Career Without Going Broke

Each will teach an identical curriculum, and not only will pupils be able to move freely between them, they will be expected to spend at least a year studying abroad as boarders.

ECONOMIST: Education