单项选择题
A、距跨中4m范围≤4mm,其余≤6mm B、距跨中5m范围≤5mm,其余≤10mm C、距跨中4m范围≤10mm,其余≤20mm
A、抗腐蚀,0.4 B、抗渗,0.4 C、抗腐蚀,0.35
A、3;塑料 B、4;塑料 C、4;砂浆