管网的定义是什么？
参考答案：管网就是出水厂后的干管至用户水表之间的所有管道及其附属设备和用户水表的总称。
Our city has developed into a big city；which is ____ it used to be. [ ]
A. four times larger than that
B. four times the size of what
C. four times the size larger than what
D. as four times the size as that
（）包括所有涉及上下游产品流、服务流、资金流和信息流中即时供应商的供应和即时客户的客户。
A.直接供应链
B.扩展供应链
C.最终供应链
