到底什么是色盲症，你又是怎么发现自己有色盲症的？

What exactly is colour-blindness and how do you find out if you have it?

《柯林斯英汉双解大词典》

但是，到底什么是组成平衡膳食的元素？

But, just what does a properly balanced diet consist of?

youdao

到底什么是标准？

What standards, anyway?

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

You smell and you think, "Is that Japanese? Is that Indian? What type of food is that?"

你使劲闻了闻，你在想“这是日本料理，还是印度菜？这到底是什么菜呢？”

What kind of 课堂 - SpeakingMax英语口语达人

It's interesting to think about what's driving that and what it means for our health and for international politics.

到底是什么导致了这些变化以及,这对我们的健康和国际政治意味着什么,这些都值得我们思考

耶鲁公开课 - 关于食物的心理学、生物学和政治学课程节选