There are still some active smallpox virus specimens kept in the world, and there are two sources of small--two places where smallpox is stored now.

世界上仍有地方保存着,一些具有活性的天花病毒样本,有两个地方还储存着天花病毒样本

耶鲁公开课 - 生物医学工程探索课程节选

If cells were actively proliferating, that is you had a population of cells that are actively proliferating, they would be going through continuous rounds of the cell cycle.

如果细胞处在活跃增殖状态,就是说有一定数量的,细胞具有增殖活性,它们就会连续地经历细胞周期的各个阶段

耶鲁公开课 - 生物医学工程探索课程节选