know-how 专门知识，技能

例句：

I'd call technical support and ask someone with the know-how.

我要打技术支持电话问个明白人。

He hasn't got the know-how to run a farm.

他没有经营农场的专门知识。

know the tricks of the trade 了解某门生意或职业的诀窍

例句：

Let's ask Tom. He knows all the tricks of the trade.

咱们去问问汤姆吧，他知道这里面的门道。

I think we need to bring in a specialist who knows the tricks of the trade.

我觉得我们需要引进一位懂行的专家。