“下部”怎么读

木桩下部结构a substructure of timber piles管子的下部可与上部分开.The lower part of the pipe is separable from the upper part.下部曲线标志出对数据对的排除域.The lower curve marks the exclusion threshold for data pairs....

“下部”的英语可以翻译为：underpart，bottom ...