短语词组短語marginal sand sheet 邊緣蓆狀砂delta front sand sheet 前緣蓆狀砂sheet sand 厚度均勻的砂巖層;平伏沙層;層狀砂層sheet sand covered 片沙覆蓋loch sheet sand 濱淺湖蓆狀砂coverage with sheet sand 片沙覆蓋frontal sheet sand 前緣蓆狀砂 返回 sand sheet