硬度（hardness）
硬度（hardness）
相关考题：
The boiler water alkalinity in a coil-type auxiliary boiler should be maintained at the pH recommended by the boiler manufacturer to______.A.precipitate(使沉淀) silica （硅石）from solutionB.reduce corrosion in the heating coilC.prevent clogging and erosion in the coilD.maintain zero water hardness
当天然水中的碱度＞硬度时，下列说法中正确的是（）。A、天然水中的〔HCO3－〕＞〔Ca2＋〕＋〔Mg2＋〕B、水中既有碳酸盐硬度，又有负硬度，而无非碳酸盐硬度C、碳酸盐硬度＝硬度，负硬度＝碱度－硬度D、水中既有暂时硬度，又有钠盐碱度，而无永久硬度E、总硬度＝暂时硬度，钠盐硬度＝总碱度－总硬度
单选题Measure （） by means of lead wire.Athe clearance of the main bearingBthe diameter of main bearingCthe hardness of main bearingDthe tolerance of main bearing
单选题Shims of different thicknesses are inserted between the shells to enable adjustment of （）.Athe bearing clearancesBthe bearing thicknessCthe bearing strengthDthe bridge hardness
单选题The boiler water alkalinity in a coil-type auxiliary boiler should be maintained at the pH recommended by the boiler manufacturer to（）Aprecipitate silica from solutionBreduce corrosion in the heating coilCprevent clogging and erosion in the coilDmaintain zero water hardness
单选题眼镜片膜层有 ①dye ②Antireflection film ③Water-proof film ④Hardness film ⑤Impact resistantfilm，膜层由表及里的顺序是（）A②③④⑤B⑤②③①C⑤④②③D②④⑤①
单选题“hardness”是（）A材料抵抗表面形变的能力，抵抗外物压入B与材料的抗张强度、抗压强度和弹性模量等性质无关