我知道，那很疯狂，不过情况就是如此。

It's crazy, I know, but there it is.

《牛津词典》

我不知道那活儿你怎么受得了。

I don't know how you stick that job.

《牛津词典》

我没必要拆开那封信—我知道里面会说些什么。

I had no need to open the letter—I knew what it would say.

《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

I don't know if it's the biggest, but it's certainly one of the best collections of stuff

我不知道那是否是最大的，但是绝对是最好的收藏之一。

世界的宝物都聚于此 - SpeakingMax英语口语达人

If you don't have the units, then if you say the answer is 19, then we don't know what it means.

如果没有的话,比如你的答案是十九,那我们就不知道这是什么意思

耶鲁公开课 - 基础物理课程节选