Management classclass此处意为：A set, collection, group, or configuration containing members regarded as having certain attributes or traits in common; a kind or category.种类：认为具有某种共同属性或特点的成员组成的一群、一套或一类；一种或一类A division based on quality, rank, or grade等级，阶层：基于品质、阶级或等级的划分
