Nevertheless, in those societies in which matrilineal descent occurs, access to socially powerful positions is mediated through the maternal line of kin. 无论如何，在那些母权宗系遗传的社会，是由母系亲属来掌握社会上最有权力的地位。
Each haplogroup is defined by set of characteristic mutations on the mitochondrial genome, and can be traced along a person's maternal line to a specific prehistoric woman. 每一个单倍组都是根据线粒体基因组的变化特征来定义，可以追溯一个人的母系遗传线索，直到一位特别的史前女性。
The surface generated by a straight line,the generator,passing through a fixed point,the vertex,and moving along a fixed curve,the directrix. 锥面由一条直线，即母线，通过一固定点，即顶点，沿一给定曲线，即准线，连续移动而产生的平面。
