关系模型允许定义3类数据约束，下列不属于数据约束的是( )。

A．实体完整性约束

B．参照完整性约束

C．属性完整性约束

D．用户自定义的完整性约束

The tools and techniques of quantitative risk analysis are______．

A．contracting，contingency planning，alternative strategies，and insurance

B．interviewing，historical results，workarounds，and additional response development

C．checklists，damage control reports，standard allowances, and inspection

D．data gathering and representation techniques，and quantitative risk analysis and modeling techniques