A. 城市发展期的供水管网 B. 城镇己达规模的供水管网 C. 城市发展成熟期的供水管网 D. 经济发达的大城市
A. 正确 B. 错误
A. Hold on. I'll get her B. No, she isn't here. C. Yes, she lives here. D. Yes, what do you want?