人一生虚度的日子，就如影儿经过，谁知道什么与他有益呢？

For who knows what is good for a man in life, during the few and meaningless days he passes through like a shadow?

youdao

首要原则是，需要锁定要谈论，即学习的目标，可是，谁知道什么是文学。

You need to pin down an object of study, a first principle from which other principles can emerge, and part of the process is to say, "Hey, it's not literature we're talking about."

youdao

谁知道他们还可能找到什么。

God knows what else they might find.

《牛津词典》

We'll never find Truth in her entirety, at least not until the Second Coming, and who knows when that will be?

我们永远找不到完整的真理，至少在第二次到来之前不能，谁知道那将是什么时候呢？

耶鲁公开课 - 弥尔顿课程节选

Right? I've allocated a variable, it happens to be a pointer; it's still a variable, who know what's in it, right?

对不？我分配了一个变量，它碰巧是一个指针，它还是一个变量，谁知道它里面是什么？

哈佛公开课 - 计算机科学课程节选

You didn't know who wrote it, where, when, how, why, and someone says to you, "I want you to draw some conclusions about that piece of writing.

你不知道是谁，在哪里，什么时间，怎么样，为什么要写,然后你被要求对篇文章，做一个总结。

耶鲁公开课 - 旧约导论课程节选