痛经

The fifth part conducted the empirical study, first selected the sampe data, through the nonparametric test and the factorial analysis, and haved established the indicator system.

第五部分进行实证研究，首先选择样本数据，然后通过非参数检验和因子分析，建立了指标体系。

The reason why people sometimes take iron supplements is that the supplements supple ment the small a mount that naturally occurs ingrains.

有时人们需要服用铁质补剂是因为这些补剂补充了谷类食物中原本含量不多的铁质。