A.可提高一級(jí),但必須經(jīng)過技術(shù)經(jīng)濟(jì)論證 B.可降低一級(jí),但必須經(jīng)過技術(shù)經(jīng)濟(jì)論證 C.可提高一級(jí),不須經(jīng)過技術(shù)經(jīng)濟(jì)論證 D.可降低一級(jí),不必經(jīng)過技術(shù)經(jīng)濟(jì)論證
A.地層特性、機(jī)械大小 B.造孔深度、機(jī)械費(fèi)用 C.墻厚、施工環(huán)境 D.地層特性、造孔深度和墻厚
A.2 B.3 C.4 D.5