mind one's own business;occupy oneself with one's own affairs;stop interfering with the affairs of other people專心于自己的事;不要管別人的閒事
You'd better go about you own business. 你還是管管自己的事吧。
I've no time to play chess with you;I've got to go about my business. 我沒有時間跟你下棋,我要幹我的事情了。