A：细胞萎缩，新陈代谢的速度减慢
B：无限增殖，失去控制
C：仍具有发育的潜能
D：细胞内的色素逐渐积累
①家长管教不严 ②有强烈的好奇心 ③学校缺乏引导 ④常常存在从众心理
Printing was developed __________ the Song dynasty in China and it __________ Asian and European countries later on.
