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(yīng)知道那個(gè)問(wèn)題的答案。

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

　　真想不到你怎么會(huì)說(shuō)出這種話來(lái)。

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

　　她不知道外國(guó)的生活會(huì)是什么樣。