Middle -aged and the elderly population

• 中老年

Middle -aged and the elderly population的用法和样例：

例句

1. Study on the correlations between serum estrogen level and heart function of coronary heart disease and the evaluation of exercise test in the middle and aged women.
   中老年妇女血清雌激素水平与冠心病心功能相关性及运动试验诊断价值的研究。