那到底是怎么发生的？

How on earth did that happen?

《柯林斯英汉双解大词典》

园艺的最大乐趣是谁也不知道到底会长出什么。

Half the fun of gardening is never knowing exactly what's going to come up.

《牛津词典》

她到底是怎么说的？

What did she actually say?

《牛津词典》

if you've got a hill or valley and there's a cart on wheels it's going to go down to the bottom.

如果我们有一座山或者山谷，并且,有一个有轮子的车，这辆车会自动滑到底部。

麻省理工公开课 - 热力学与动力学课程节选

It's always worth asking yourself what a line of poetry that is as aggressively unpleasant as this one is doing in a poem.

你需要不断的问自己，一句让人感到被侵犯，不悦的诗,正如这里的这句，到底想要表达什么。

耶鲁公开课 - 弥尔顿课程节选

We started off talking about binary search, and I suggested that this was a log algorithm which it is, which is really kind of nice.

我告诉了你们这是一个对，数级的算法，这是很棒的,我们来一起看看这个算法到底做了什么。

麻省理工公开课 - 计算机科学及编程导论课程节选