I want to know everything, but realize that nothing can ever be known for sure.

我想知道的一切，但实现没有什么可以被称为肯定。

youdao

Therefore, the goodness or the betterness of strategies as projections of some future outcomes will never be known for sure until they have been tried.

因此，在战略被尝试之前，它们作为对某种未来结果的预测的益处或优点将永远无法确切地知道。

youdao

I'm not sure what my sister would have done had she known that she wouldn't be here for the tomorrow we all take for granted.

如果我的妹妹知道她明天会死去，我不确定她可能会做些什么，因为我们都以为明天是理所当然的。

youdao

Whether the stampede was a tragic accident or the result of a deliberate attack may never be known for sure.

ECONOMIST: An Iraqi tragedy raises sectarian tension | The

She's known for niceties like sending thank you notes, and her office has a tracking system to be sure they are sent out.

WSJ: Giffords Shows Encouraging Responses