For most of us, we can go up to three dimensions because we know we live in a three-dimensional world.

对于大多数人来说,我们最多可以考虑三维,因为我们生活在一个三维世界

耶鲁公开课 - 基础物理课程节选

There are only three people left in Britain who fought in World War One, only three, and they're about 110-years-old or something like that.

在英国,一战老兵,只剩下三个了,就三个,他们得有,大概110岁

耶鲁公开课 - 1871年后的法国课程节选

We are able to talk about the fact that two plus one equals three, but it's not as though we ever come across numbers-- number three itself--anywhere in the empirical world.

我们可与去探讨,二加一等于三的这个事实,但是我们不可能有一天真的碰到数字,在现实世界中碰到个叫"数字三"的东西

耶鲁公开课 - 死亡课程节选