Hold your horses.=Be patient
耐心点儿

Be quick.
快点儿！

It will do you good.=it's good for you.
这个对你有好处

Give my best to your family.
代我向你全家问好

What brings you here?
什么风把你吹来了？

I'll pick up the tab.=I'll pay for it.
我来买单