不同密度等级绕制滤心的聚酯纤维
graded-density spun polyester
不同强度等级
Different degradation degree
不同强度等级混凝土
different strength grade concrete
concrete with different strength grade
对偶电路实验室精度等级试验仪表
laboratory quality dual circuit precision test gauge
风功率密度等级
Classes of wind power density
钢筋强度等级
intensity grade of reinforcing steel bar