自然死亡系数
instantaneous rate of natural mortality
线描自然率真
natural and lifelike line drawing
纠缠突然死亡与突然产生
entanglement sudden death and sudden birth
4周死亡率
mortality rate in fourth weeks
5岁以下儿童死亡率
Child under 5 years old mortality rate
Child Mortality under age 5 years old
Under 5 Mortality Rate