A:细胞核变为精子头部的主要部分
B:高尔基体发育为头部的顶体
C:中心体演变为精子的尾
D:线粒体退化消失
–Li Na won the tennis championship in the French Open an June 4, 2011.
-We take pride in her. She is the first Asian professional tennis player to win it.
写出下列各命题的逆命题,并判断原命题和逆命题是不是互逆定理.
(1)相等的角是内错角;
(2)角平分线上的点到角的两边的距离相等.
交警在查“酒驾”时,先请司机打开车窗,若闻到酒精气味,则要求司机必须接受酒精含量的测试。交警能闻到酒精气味是因为酒精()