“我不知道他们为什么离开，”他悲伤地说。

"I don't know why they left," he said dolefully.

《柯林斯英汉双解大词典》

例如，观众通过一封信或其他人的谈话得知这位神秘的绅士是谁，以及他多年前为什么离开这个城市。

For example, the audience learns through a letter or through someone else's conversation who this mysterious gentleman is and why he left the town many years before.

youdao

你为什么离开银行呢？

Why did you leave the bank?

youdao

We'll see why they have to separate that in a minute, but they do that these lipid bi-layers solve that problem for them and they're self-assembled structures from these molecules called phospholipids.

我们马上会讲到为什么要把它们隔离开,脂质双层膜解决了这个问题,而这些自主装结构,就是由磷脂分子组成的

耶鲁公开课 - 生物医学工程探索课程节选

Why did you decide to leave Australia and come to London?

你为什么决定离开澳大利亚来到伦敦呢？

从澳大利亚到英国 - SpeakingMax英语口语达人

If you ask the question why did many Italians leave their homes, especially south Italians in the late nineteenth century and come-- well, go all over the world actually, to South America, Australia, but the largest numbers to the United States.

如果问及为什么很多意大利人离开家乡,特别是十九世纪居住在意大利南部的人们,事实上他们的足迹遍布全球,南美,澳大利亚,但更多的是到美国来了

耶鲁公开课 - 古希腊历史简介课程节选