下列哪一项是数据仓库阶段的特点（）
A.提供预测性数据信息
B.提供回溯性的动态数据信息
C.提供静态的数据信息
D.提供历史性的动态数据信息
参考答案：B
病人对手术的耐受能力，可分为那两类？
As one of the tools and techniques of activity sequencing, a lead （）.
A．directs a delay in the successor activity
B．could be accomplished by a finish to-start relationship with a delay time
C．means the successor activity cannot start until after the predecessor is completed
D．allows an acceleration of the successor activity
