His uncle would rather ___________ the old bike than ___________a new one.
A:repair, to buy
B:to repair, buy
C:repair, buy
D:to repair, to buy
已知圆锥的底面半径为3,体积是12π,则圆锥侧面积等于____
①称取一定量的固体铁氧体磁性材料溶于过量盐酸,接着先后加入双氧水和氢氧化钠溶液,静置24h,过滤
②将沉淀加入反应瓶中,加入过量的氢氟酸溶液,80℃恒温加热24ha
③蒸发多余氢氟酸和水,得淡红色FeF3凝胶
④在干燥箱中,以100℃预处理6h,最后掺入铁氧体磁性材料混合研磨制得正极材料