Sorry I can't afford to sit here and chat with you all day. I have bigger fish to fry.

很抱歉我不能整天坐在这儿和你瞎侃。我还有更要紧的事要做。

Shirley: Oh, sorry. I have bigger fish to fry. I have to prepare for tomorrow's conference.

雪莉：哦，真抱歉。我有更重要的事要做。我得准备明天的会议。

I have got bigger fish to fry.

我有比较重要的事要办。