A.3mm B.6mm C.9mm D.5mm
A.5mm B.8mm C.10mm D.12mm
A.单坡长度的1/800,且不大于30 B.单坡长度的1/800,且不大于25 C.单坡长度的3/800,且不大于25 D.单坡长度的3/800,且不大于30