category of ring

例句：

1. 1.Different categories of animals are found in the forest.
   森林中有不同的动物种类。
2. 2. The teacher categorized the students into different groups for better understanding.
   老师将学生分为不同的小组以便更好地理解。
3. 3.This category of products is suitable for people with allergies.
   这种产品的类别适合有过敏体质的人。