题目

My sister______ her cat yesterday，but she didn't__ _ it. A．found；look for  B．looked；found C．looked for；find 答案：C18．0.5L 0.2mol/L的Al2（SO4）3中含有n（Al3+）0.2 mol，m（SO42-）28.8g．某硫酸钠溶液中含有3.01×1022个Na+，则该溶液中SO42-的物质的量是0.025mol．