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！你看誰來啦！

　　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問題的答案。

　　I don't know how you can say things like that.

　　真想不到你怎么會說出這種話來。

　　She didn't know what life in a foreign country would be like.

　　她不知道外國的生活會是什么樣。