业主将工程建设任务发包给专门从事项目组织管理的单位，再由它分包给若干设计和材料设备供应单位，并在实施中进行项目管理是指( )。

A．平行承发包模式
B．设计或施工总分包模式
C．项目总承包模式
D．项目总承包管理模式

— Tom is never late for work. Why is he absent today?

— Something _____ to him. [ ]

A. must happen                                    

B. should have happened

C. could have happened                              

D. must have happened