机器人到底是什么呢？

What exactly is a robot?

youdao

钻石到底是什么呢？

What is diamond after all?

youdao

“火烧人”到底是什么呢？

What exactly is Burning Man?

youdao

So what is this all about? What is an object in object-oriented programming?

所以它到底是什么呢？,面向对象编程中的对象到底是什么呢？

麻省理工公开课 - 计算机科学及编程导论课程节选

And if it's a poet that you want to be, to what extent can the writing of poetry be considered respectable work?"

如果你想要成为一位诗人，写诗到底是什么,体面地工作呢？“

耶鲁公开课 - 弥尔顿课程节选

Then you start to wonder well what is the system and ? what is it supposed to do?

于是你开始质疑,这个系统到底是什么,还有它到底是要干什么呢？

耶鲁公开课 - 金融市场课程节选