We cannot guess his motives. We just have to deal with the reality: that a North Korea that is proliferating weapons and missiles is a serious threat and danger to the world."

VOA: standard.2009.06.14

The red blood cells that carry oxygen only live within your circulation for about a month and so you have to continually be replacing cells that are dying and so there are cells that are proliferating.

携带氧的红细胞,在你的循环系统中的寿命只有一个月,因此你必须持续不断地更新衰老的细胞,所以就有在增殖的细胞

耶鲁公开课 - 生物医学工程探索课程节选