华人作家龙应台说:“如果你撑着伞溜达一阵,发觉裤脚虽湿却不肮脏,交通虽慢却不堵塞……这大概就是个先进国家……”优良的排、蓄水系统如同健康的心脏和血管,保证城市正常的循环、代谢和安全。伦敦和巴黎的下水道系统已有 Chinese writer Long Yingtai said: “If you hold an umbrella stroll for a while and found that the trousers are not wet but dirty, the traffic is slow but not blocked ... This is probably an advanced country.” The system acts like a healthy heart and blood vessels, ensuring the city’s normal circulation, metabolism and safety. Sewer systems in London and Paris already exist