— I am really surprised that a policeman in his car _____ have hit several common pedestrians, killing

     one and injuring three.

— Yes, If one _____ ask for trouble, what can we say?[ ]

A. would, will

B. must, may

C. should, must

D. need, dare

在计算机应用中,CAD和CAM是典型的信息系统。它们属于________。

A．管理业务系统

B．辅助技术系统

C．信息检索系统

D．信息分析系统