There is A many-to-many connection between entity A and entity B. In order to describe the association relationship between them, link C is added to associate entity A and B, so the connection between C and B is also many-to-many.
This is because the association between entity A and entity B is many-to-many, that is, an entity A can be associated with more than one entity B, and an entity B can be associated with more than one entity A. Therefore, in order to associate entities A and B, A link C needs to be introduced, which may be associated with multiple entities A and B. Therefore, the connection between C and B is many-to-many.
