One is that there's four different colors and so you can see red, blue, yellow, green here - four different colors and that's all there are, there aren't more than four.

一是这些梯阶有四种不同颜色,你可以看到红 蓝 黄 绿,恰恰只有四种不同颜色,不多不少

耶鲁公开课 - 生物医学工程探索课程节选

In this diagram I'm showing you it's easy to tell because some are yellow, and some are pink, and some are blue but that's not the way they come out of the bone marrow.

在我给你们看的这张图表中很简单,因为其中一些细胞是黄色的,有些是粉红的,有些是蓝的,但它们在骨髓里没有这些颜色

耶鲁公开课 - 生物医学工程探索课程节选