packsand

例句：

1. 1.The soldiers used the packsand to build a fortress.
   士兵们用沙袋建造了一个堡垒。
2. 2. The engineers used the packsand to reinforce the foundation of the building.
   工程师们用沙袋加固了建筑物的基础。
3. 3. The children played with the packsand and built sandcastles.
   孩子们用沙袋玩耍并建造沙堡。