underdrainage英'ʌndə,draɪnɪdʒBNC¹⁷³⁹⁹⁵⁺² 基本例句 n.地下排水¹⁰⁰ By analysis of difficult points in underdrainage design at excavation section, the paper briefly introduces thinkings and methods for underdrainage design at excavation section. 通过对挖方段暗排设计难点的分析，简要介绍挖方段暗排设计的思路及方法。 cnki