How should I know where you've left your bag?

我怎么知道你把包丢在哪儿了？

《牛津词典》

"No," answered he, "how should I know?"

“不。”他回答，“我怎么会知道？”

youdao

She didn't know. How should I know?

她都不知道，我怎么会知道？

youdao

I think you should take the lab sometime, but I don't know how many semesters that you have to take.

我觉得你们应该是不是地去做几次实验,我不太清楚你们要上多少个学期的课

耶鲁公开课 - 基础物理课程节选

We have to know what to pay attention to People who are not good in focusing their attention on the right things -I'm not just talking about attention deficit disorder, I'm talking about some more high-level question of how you know what you should be paying attention to.

我们需要知道哪些值得注意,那些主次不分的人,我谈论的不仅是注意力不足过动症,还有在面对复杂问题时,你如何知道哪些事情值得关注

耶鲁公开课 - 金融市场课程节选

No one can say for certain how this change will end, but I do know that change is not something that we should fear.

WHITEHOUSE: President Obama Speaks to the People of Brazil

And I know all too well how difficult it is to throw off the yoke of the should do success techniques.

FORBES: Finally, Success Tips that Work

Indeed we have been ourselves, you know I set up the review, the balance review of how much the government should be paying in local council tax contribution because it's made up of council tax by the local authorities and national.

BBC: NEWS | Programmes | Breakfast with Frost | Council Tax capped?