Now the question you'd need to ask yourself is how do you know this didn't happen to you last night?

现在你要问自己的问题是,你怎么知道,昨晚你没发生这样的事？

耶鲁公开课 - 死亡课程节选

But if you say, well, I don't know how to do this, I am not going to bother, don't grade the paper.

但是如果你说，好吧，我不知道怎么做这个，我想麻烦，别给试卷评分。

麻省理工公开课 - 固态化学导论课程节选

How do you know something like this doesn't happen every single night, every hour on the hour, ? every minute, every second?

你怎么知道这样的事,每一晚，每个小时，每分每秒都没有发生？

耶鲁公开课 - 死亡课程节选

And a sympathetic but frustrated fan of the filmmaker's stories and characters is entitled to ask, why doesn't "How Do You Know" know what to do from scene to scene?

CNN: Review: 'How do you know' when a movie doesn't connect?

But if you're someone who's bought a piece of technology that you can't use or you don't know how to fully use, what should you do?

NPR: Tips for Fighting Technology Overload

You don't really know how much you can do until you stand up and decide to try.

WHITEHOUSE: It's Work Creating Jobs, But It's Worth It