属于人口统计指标的是（）。
A.婴儿死亡率
B.出生率
C.死因别死亡率
D.平均预期寿命
E.病死率
参考答案：B
When he moved to Germany in _____ , he was already in _____ .[ ]
A. the 50s; his sixty
B. the 50s; his sixties
C. 50s; his sixties
D. 50s; his sixty
试述市场细分化的产生历程。
