[单选] The boiler water alkalinity in a coil-type auxiliary boiler should be maintained at the pH recommended by the boiler manufacturer to（）
A . precipitate silica from solution B . reduce corrosion in the heating coil C . prevent clogging and erosion in the coil D . maintain zero water hardne
简述浆纱的要求。
若电网发生铁磁谐振过电压时应如何处置？
监管物中材质单涉及到的元素符号，需要我们识别：铁（）铜（）锰（）铝（）铬Cr。
简述分批整经技术措施。
人与体内大肠杆菌都有的代谢途径有（） 糖酵解。 乳酸发酵。 三羧酸循环。 尿素循环。
The boiler water alkalinity in a coil-type auxiliary boiler should be maintained at the pH recommended by the boiler manufacturer to（）
