"No one knows what has happened.

VOA: special.2010.05.29

I think that might be the reason- no one knows what all their reasons were.

我认为也许这就是原因-,没有人知道他们所有的原因是什么。

耶鲁公开课 - 金融市场课程节选

But experts say no-one knows how large the world stockpile of nuclear material is because not every country reports what it's producing.

VOA: standard.2010.04.06