可变组成指数
参考答案：
指反映组平均水平和总体结构两个因素综合数量变动的指数，即反映总平均水平变动的指数。
—Amy, I called you yesterday evening, but nobody answered the phone.
—Oh, I _______ a walk with my mother at that time. [ ]
A. take
B. took
C. am taking
D. was taking
物流企业为客户对其物流系统一体化的功能整合就是增值服务。
