impolite
不礼貌的   

例句：
It is impolite behavior to smoke in public.
在公共场所吸烟是不礼貌的。

know one's beans
熟悉（精通）自己的业务
 
例句：
Though she is very clumsy at doing housework, she knows her beans in working.
虽然她在做家务方面笨手笨脚的，在工作方面却很精通。

Make yourself at home.
不必拘束。 

对话：
A: I'm so glad you could come, please make yourself at home.
B: Thank you.
A: Did you have any trouble finding our home?
B: No, not at all.
　　　
A：非常高兴你能来，请不必拘束。
B：谢谢！
A：找我家困难吗？
B：哦，一点儿也不。