单项选择题
A.entO is in a defined state
B.enO is currently active
C.There is no physical network adapter on the system
D.The address 172.168.0.50 is in use by another system
单项选择题 AnadministratorreceivedacallfromauserwhosePCcrashedwhileusingvitoeditafile.Theuserwantstheeditedfileback.Whereshouldtheadministratorlookforthefile（）
单项选择题 UnderwhichofthefollowingcircumstancesmustaJFSfilesystembeusedinsteadofaJFS2filesystem（）
单项选择题 Anadministratorneedstochangeasystem’srunlevelfromlevel2tolevel3.Whatistheappropriatemethodtoaccomplishthis（）