I'm paying lots of money for you, so you'd better do well.
我为你花了那么多钱,所以你要好好干。
Which of your arms is sore?
你哪个手臂酸呀?
As far as I could see, it needed only a minor adjustment: a turn of a screw here, a little tightening up there, a drop of oil and it would be as good as new.