The stereotyped sex roles in textbooks do not fit well with reality. 教科书里刻板的性别角色，与现实环境并不尽符合。
This scarcity reverses normal gender roles, because females are in demand in populations with an equal sex ratio. 雄性成为稀有动物之后，传统的性别角色都颠覆了，因为在性别比例平衡的情况下，待价而沽的是雌性。
