A.20%~30%B.30%~40%C.40%~50%D.50%~60%
A.10mg/LB.15mg/LC.20mg/LD.25mg/L
A.夯管錘的沖擊力大小B.鋼管的內(nèi)徑C.土層的性能D.鋼管壁厚