n.地堑
A graben creates a favourable setting for uranium deposition. 地堑成为铀矿沉积的有利部位。
The present Yinchuan graben is not the separated line of Helanshan Basin and Ordos Basin. 现今的银川地堑当时也并不是贺兰山盆地与鄂尔多斯盆地的分割。
