A.截水帷幕 B.降水井 C.排水溝 D.基坑
A.不施工 B.從上到下進(jìn)行開(kāi)挖 C.分層開(kāi)挖,挖好-層施工-層 D.分段開(kāi)挖,挖好-段施工-段
A.20 B.40 C.60 D.80