circulation sand

例句：

1. 1. The river's circulatingsand is causing a lot of problems forthe local residents.
   这条河的循环沙给当地居民带来了很多问题。
2. 2. The engineer usedcirculating sand to build the foundationof the new bridge.
   工程师使用循环沙来建造新桥的基础。
3. 3. The sandin the desert is constantlybeing circulated by thewind and water.
   沙漠中的沙子被风和水不断地循环着。