A．They were inexpensive.

B．It was fashionable to wear them.

C．They were a sign of wealth.

D．It was important to be on time.

绘制矿井通风网络图的目的是（）。

A．找出风流通过的井巷谁长，谁短

B．找出通风井巷的空间关系

C．分析通风系统中风道的连接关系及其特点

D．判断通风的难易程度