The schedule control process for a project ______ .

A．focuses on starting the project earlier than scheduled

B．is necessary for controlling changes to the project schedule

C．is concerned only with activities that are on the critical path

D．should focus entirely on activities that are difficult to carry out

公关危机最为明显的特征是（ ）

A．不确定性

B．突发性

C．连锁破坏性

D．溢出效应