A.200B.250C.300D.350
A.15 B.20 C.25 D.30
A.層高不大于5m時為6mm,層高大于5m時為8mm B.層高不大于5m時為8mm,層高大于5m時為6mm C.層高不大于5m時為7mm,層高大于5m時為5mm D.層高不大于5m時為5mm,層高大于5m時為7mm