细胞核中储存遗传信息的物质是( )
A:染色体
B:DNA
C:蛋白质
D:糖类
Helen has picked up French and can speak fluently after a short stay with her aunt in Paris.
读某社区(左图),居民购物活动圈层结构图(右图)及各圈层特点统计表,完成下列各题。
由于血缘关系的亲疏不同,西周贵族集团形成的宗法等级序列应该是