单项选择题
A.5B.8C.15D.20
A.块状B.片状C.粒状D.长条状
A.20B.30C.40D.50
A.5B.10C.15D.20
A.破碎看断口B.敲击听声音C.打磨看火花D.铲削看铁屑
A.破碎看断面B.敲击听声音C.打磨看火花D.铲削看铁屑
A.8%B.10%C.12%D.14%
A.90%B.85%C.81%D.77%
A.1/5B.1/6C.1/7D.1/8
A.1/8B.1/10C.1/12D.1/14