预应力混凝土梁钢筋张拉时,其钢筋的实测伸长值与相应的理论计算差值应控制在()以内。
A.10%
B.6%
C.5%
D.3%
参考答案:B
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