A.采用CBR5 B.采用CBR2.5 C.CBR2.5和CBR5 D.不采用任何值
A.7mm B.2.5mm C.1mm D.2mm
A.R=0.012526P/H B.R=0.006263P/H C.R=0.004178P/H D.R=0.00051P