基本重合原则
参考答案:
要尽可能选用设计基准作为精基准,即遵循基准重合原则。特别是在最后精加工时,为保证加工精度,更应遵循这个原则,这样可以避免由于基准不重合而引起的误差。
-Here are three books on history. Which one would you like to borrow?
-______. You see, I'm interested in geography these days. [ ]
A. All
B. None
C. Both
D. Each
某高压汽包炉,蒸发量为360t/h,炉水容积为90m3 ,给水SiO2=18.0ug/L,饱和蒸汽SiO2=13.0 ug/L,炉水SiO2=1.2mg/L,求锅炉排污率?若昼夜不排污的话,昼夜炉水SiO2浓度增加多少?