A.管壁厚度 B.溝底深度加視線高度 C.管壁厚度減去1cm D.管壁厚度加基礎(chǔ)厚度
A.0.5 B.1 C.1.5 D.2
A.50% B.55% C.60% D.65%
A.2‰ B.3‰ C.1% D.3%~5%