hard aggregate

例句：

1. 1. The engineer used a special machine to crush the hard aggregate.
   工程师使用一种特殊的机器来粉碎硬聚合体。
2. 2.The construction workers were required to wear hard aggregate-resistant gloves.
   建筑工人被要求佩戴能抵抗硬聚合体的手套。
3. 3.The hard aggregate in the soil can be a good indicator of its fertility.
   土壤中的硬聚合体能作为其肥沃程度的一个良好指标。