who can say 

used for saying that no one knows the answer to a particular question or knows what will happen in the future

在表達(dá)沒有人知道一個特定問題的答案，或者知道未來會發(fā)生什么時，我們會使用這個短語

A: What does the future hold, now that you've left the music industry?

既然你已經(jīng)離開了音樂行業(yè)，你的未來會怎樣?

B: Who can say, really? I've always been interested in writing a novel, so I may pursue that.

說真的，誰知道呢?我一直對寫小說感興趣，所以我可能會從事寫作。