单项选择题
A.12000~24000B.1200~2400C.12000~20000D.10000~20000
A.8B.10C.8~12D.8~10
A.目数应不小于320目B.应不小于320目C.颗粒度目数应不小于400目D.颗粒度目数应不小于320目