human population的用法和样例：
例句
- The birth rate is the number of births compared to the size of the population.
出牛率是出生人数与人口总数之比。 - That number is so small that even with the reduced child mortality which usually accompanies development it cannot possibly sustain the population.
这个数值非常低，即便随着社会的发展，婴儿死亡率已下降，如此低的出生率仍可能难以维持人口总数。
