多重性：您可以指派两个实体之间的关系具有多重性。例如，每一节篮子编织课程上必须有20到30名学生。
Multiplicity: You can designate the multiplicity of a relationship between two entities — for instance, each basket-weaving class must have between 20 and 30 students.
多重性：您可以指派两个实体之间的关系具有多重性。例如，每一节篮子编织课程上必须有20到30名学生。
Multiplicity: You can designate the multiplicity of a relationship between two entities — for instance, each basket-weaving class must have between 20 and 30 students.
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