你昨天晚上八点钟在做什么？

What were you doing at eight last night?

youdao

你昨天的这个时候在做什么？

What were you doing this time yesterday?

youdao

昨天我给你打电话时你在做什么？

What were you doing yesterday when I called you?

youdao

That slide is on your--is in the slides that are distributed if you want to follow on that website, there's the picture that I copied yesterday.

在发给你们的幻灯片里,如果你想在那个网站上做深入了解,这是我昨天从网站上拷贝下来的一张图片

耶鲁公开课 - 生物医学工程探索课程节选