foul clay

例句：

1. 1.The river flows through a region with foul clay soil.
   这条河流流经一个地区，那里的土壤是黏土。
2. 2.The farmer had to dig his way out of the foul clay.
   农民不得不挖出一条出路，穿过黏土。
3. 3. Foul clay is difficult to remove from buildings.
   黏土很难从建筑物中清除。