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

需要积极抗病毒治疗的乙型肝炎有（）

A.乙肝表面抗原携带者

B.乙肝后肝硬化

C.重症肝炎

D.病毒复制活跃的慢性肝炎

E.急性乙型乙肝恢复期