I don't know what you're on about.

　　我不懂你在談什么。

　　Well, what do you know? Look who's here!

　　唷，真想不到！你看誰(shuí)來(lái)啦！

　　She of all people should know the answer to that.

　　在所有的人中，唯有她最應知道那個(gè)問(wèn)題的答案。