树木死亡出生率
tree mortality and recruitment
多路输出比例电路
proportion circuit with multiple outputs
输入与输出比例因子
input and output scale factor
固定比例生产函数
fixed-proportional function
可变比例生产函数
variable proportional function
师生比例
the ratio of teachers to pupils
师生比例会较低
the teacher-to-class ratio will be higher
衍生比例定律
derivative proportional law