名 age，years，length of time，duration，instar ；

[例句] 对缓慢置换,假设的时龄分布函数变得不重要. For slow replacement the age distribution function assumed is unimportant.

[例句] 器官在早的龄期内不致被缩小或呈退化状态. The organ will not be reduced or rendered rudimentary at this early age.