Longitudinal or seif dunes are dunes that are parallel to a strong wind that blows in one general direction.
纵向或者赛夫沙丘是与强风平行的沙丘,风总是以相同方向刮过。
The step portion has an annular convex portion joined to an annular concave portion and displaces at least a portion of the center panel vertically in a direction parallel to the longitudinal axis.
台阶部分具有环形凸形部分,该环形凸形部分与环形凹形部分连接,并使得中心面板的至少一部分沿平行于纵向轴线的方向而垂直位移。
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