alluvial placer造句

例句與造句

1. The location of most Yogo sapphires within igneous rock rather than from alluvial placer deposits requires difficult hard rock mining.
2. In addition, there are twenty-three fields of alluvial placer gold in the region ( nineteen of which were being developed and prospected in 2006 ) and seven residual soil gold fields suitable for open-cut mining in the southeast.
3. It's difficult to find alluvial placer in a sentence. 用alluvial placer造句挺難的