物流管理信息系统把大量的事务性工作交给计算机来完成，使人们能够把精力集中在（）的研究中。

A.管理思想

B.管理目标

C.管理决策

D.管理对象

—Did you visit the famous cultural relics last month?

—No,we _________ it,but we spent too much time shopping.

A．could have visited

B．must have visited 

C．can’t have visited

D．shouldn’t have visited 