单项选择题
A.1/5~1/10 B.1/10~1/20 C.1/20~1/50 D.1/50~1/100
A.2m×0.5m×0.5m B.2m×2m×1m C.2m×lm×0.5m D.1m×lm×0.5m
A.聚乙烯苯板 B.炉渣 C.水泥 D.高分子材料