单项选择题
A.1~2mmB.1~3mmC.1~4mmD.1~5mm
A.30mmB.25mmC.20mmD.15mm
A.自上而下、先岸坡后河槽B.自上而下、先河槽后岸坡C.自下而上、先岸坡后河槽D.自上而下、先河槽后基础