With such a long interval, it is difficult to determine the age of this fossil.
时间隔得这么久了，很难确定这化石的年代。
2
The age at death for early child mortality was determined by the mean interval between successive births and the mean age of neonates at registration.
幼儿死亡率的死亡年龄由母亲相继生育的平均时间间隔和婴儿出生登记时的平均年龄决定。
3
The interval between gestational diabetes and diagnosis of pancreatic cancer ranged from 14 to 35 years; median age at diagnosis of cancer was 58 (range 42 to 76).