1·Menstruation may cease when a woman is anywhere between forty-five and fifty years of age.
月经可能在女性45至50岁之间停止。
—— 《柯林斯英汉双解大词典》
2·Women, during menstruation, should use clean, soft cloth or sanitary napkins.
女士在月经期间应该选用干净、柔软的软布或卫生巾。
3·Menstruation (a period) is a major stage of puberty in girls; it's one of the many physical signs that a girl is turning into a woman.
月经（例假）的来到是女孩青春期中经历的一个重要阶段；它是女孩变为女人的众多生理变化之一。