一旦钱花光了，我们就不知道该怎么办了。

We didn't know how we would cope once the money had gone.

《牛津词典》

如果没有广告，我们就不知道有什么好买的。

We wouldn't know what there was to buy if we didn't have advertisements.

youdao

除非我们认真听，否则我们就不知道怎么回答。

Unless we listen carefully, we can't know how to respond.

youdao

if we can't think what system it belongs to, that's tantamount to saying we really don't know what it is.

我们就不知道它从属于哪个符号系统，我们就不能认识它了。

耶鲁公开课 - 文学理论导论课程节选

Well, that matters to us, but the trouble is, without predictability you don't know where to put the peak.

那对我们很重要，但问题是，没可预见性你就不知道巅峰放在哪点。

耶鲁公开课 - 死亡课程节选

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