In the pale light of the tunnel, 30-foot fossil traces of lycopsid gleam slickly in the shale roof like alligator skins.
在隧道内黯淡的灯光下，页岩顶部30英尺长的石松化石遗迹就像鳄鱼皮般发出柔滑的光亮。
The oil shale can be used as construction materials, such as high grade cement filler, light concrete bone material-pottery grain and light brick materials, etc.
油页岩渣可用作建筑材料，如高档水泥填料、轻质混凝土骨料陶粒及轻质砖材料等；
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