American women usually consider their best friend as someone ________ they can talk frequently.

A．who

B．whom

C．about which

D．with whom

某双代号网络计划如下图所示，途中存在的绘图错误有（）

A．多个终点节点

B．节点编号重复

C．两项工作有相同的节点编号

D．循环回路

E．多个起点接点