Not until I reminded him for the third time _____ working and looked up.

A．that he stopped

B．does he stopped

C．did he stop

D．that he stopped

J．Martin指出，系统开发所建立的企业模型应具有若干特性，以下哪个不在其要求之列

A．完整性

B．适用性

C．持久性

D．灵活性