We'll talk about how your normal valves function inside your heart and how your heart couldn't work in the way that it did if it didn't have valves that were doing a very complex operation many many times a day.

我们会讨论,正常的瓣膜在心脏中如何工作,以及没有这个,每天不停完成很多复杂任务的心脏瓣膜,心脏为什么,就不能正常工作了

耶鲁公开课 - 生物医学工程探索课程节选

But in your heart you know it can't be done by today.

但你心里清楚今天是不可能做完的。

I don't know 课堂 - SpeakingMax英语口语达人