What did you say?你说什么。
具体场景：
1、如果是两人去吃饭等场景，需要一人做出决定，如
A：Would you like to eat Chinese food or Japanese food?
B：it's up to you. （你做决定吧，你说吃什么就什么）
2、what are you talking about? 自己加强语气.
一般的话,what are you saying? 就行了.
3、I have no idea what you're saying!不知道有没有拼错!可是如果伱要惊讶的话,就是这句了!
say v. 说，讲
〔辨析〕最普通用词，指用语言表达思想，侧重于所说的具体内容，通常用作及物动词。
speak v. 说（话），讲话
〔辨析〕用作不及物动词时，侧重指说话的动作而非内容，可指长篇演讲或三言两语的交谈，也可指简单的开口说话的能力；用作及物动词时，其宾语常为某种语言。
1、你说什么？
What d'you say?
2、“好吧，你说什么都行，”他和气地同意了。
'OK, whatever you say,' he had agreed peaceably.
3、他心不在焉，你说什么他都没听见。
His thoughts were far away and he didn't hear a word of what you said.
凯大大!
