近几年，为治理城镇污水，污水处理厂的建设不断升温。大规模上马污水处理厂，的确能在短期内实现城镇生活污水COD的减排。但是，一些地方城镇生活污水经过鱼塘和天然湿地的生态净化，COD浓度也能大幅度降低。由此推出：

A．单一的集中治理模式不符合环境保护自身的规律

B．治污就是要付出消耗能量和资金的代价的

C．减排手段应因地制宜，多种方式相结合

D．为治污而治污，不能将节能与减排结合好

Which is the proper method of determining whether a portable CO₂ fire extinguisher needs recharging?（）

A.Check the tag to see when the extinguisher was last charged

B.Release a small amount of CO₂; if the CO₂ discharges，the extinguisher is acceptable

C.Weigh the extinguisher and compare the weight against that stamped on the valve

D.Recharge the extinguisher at least once each year