inclusion relation for sets

例句：

1. 1. In thestudy of mathematics, the inclusive relation between a set and itselements is crucial.
   在数学研究中，集合与其元素之间的包含关系至关重要。
2. 2. The inclusive relation between two sets can beused to determine their intersection.
   两个集合之间的包含关系可以用来确定它们的交集。
3. 3. The inclusive relation between two sets allows usto define the union of the sets.
   两个集合之间的包含关系允许我们定义集合的并集。