工程清单表中项目编码的第一级为( )。

A．分类码

B．具体清单项目码

C．节顺序码

D．清单项目码

Mr White____at 8:30 for the meeting, but hedidn't show up. [    ]

A. should have arrived    

B. should arrive

C. should have had arrived    

D. should be arriving