某钢铁厂每天需消耗5000t含Fe3O476%的磁铁矿石.该厂理论上可日产含杂质4%的生铁的质量是多少?(计算结果精确到0.1)
(Ⅰ)求证:A1B∥平面B1CD;
(Ⅱ)当三棱锥C﹣B1C1D体积最大时,求点B到平面B1CD的距离.