a syndrome that occurs in many women from 2 to 14 days before the onset of menstruation
例句
用作名词 (n.)
What are typical premenstrual symptoms? 经前综合症有甚麽症状？
The female endocrine system is highly complex and medical experts still do not fully understand the chain of events that causes premenstrual symptoms. 医学界已确定女性的身体会释放不同的贺尔蒙来控制生理周期，但是经前综合症的成因尚未完全掌握。
美
