To identify whether a judgment is a relational judgment, it depends on whether it determines the nature of the object or the relationship between the objects. If it determines the nature of the object, it can only be a judgment of nature. If a sentence can be split into two Or two or more simple property judgments, then it is also a property judgment; if the relationship between objects is determined, it cannot be divided into two or more simple nature judgments, so that this judgment can be determined as Relationship judgment. Therefore, among the following items, the relationship judgment is:. ['A is a party member.', 'A and B are party members.', 'A and B are concurrent.', 'A is a party member and class cadre.']