根据百分数的意义，这里是把99粒种子看做单位“1”，
所以发芽率是100%．
故选：C．
258. As soon as the principal ______ the news on the bulletin, the students began gathering in the school garden.
A．mailed
B．sent
C．posted
D．Handed
有机磷酸酯类对神经系统的毒性作用主要损害（）
A.神经元
B.轴索
C.髓鞘
D.神经递质
E.以上都
