单项选择题
A. DB_RECOVERY_FILE_DEST only
B. DB_FLASHBACK_RETENTION_TARGET only
C. DB_RECOVERY_FILE_DEST_SIZE and DB_RECOVERY_FILE_DEST only
D. DB_RECOVERY_FILE_DEST and DB_FLASHBACK_RETENTION_TARGET only
E. DB_RECOVERY_FILE_DEST_SIZE， DB_RECOVERY_FILE_DEST and
F. DB_FLASHBACK_RETENTION_TARGET
单项选择题 InwhichscenariowillyouusetheFlashbackVersionQueryfeature？（）
单项选择题 YouareworkingasaDBAatNetFxCorporation.YoudiscoverthattheSCOTTschemaisdeletedbymistake.Youdecidetoflashthedatabasebacktothetimewhentheschemaexisted.Whichviewwillyouquerytodeterminetheestimatedsizeoftheflashbackdatathatyourequireforyourcurrenttargetretention？（）
单项选择题 YouhavejoinedaneworganizationasaDatabaseAdministrator.TheSecurityAdministratorinyourorganizationhaskepthumanerrors，suchaserroneouslydroppingusers，tables，andimportantdata，toaminimumbycarefullygrantingonlythenecessaryprivilegestoeachuser.Asaresultofseveralongoingtransactionswithinyourdatabase，youdiscoverthattheflashbacklogsarerapidlyincreasingintheflashrecoveryarea.Toavoidout-of-spaceerrors，youdecidetodeletetheflashbacklogsfromtheflashrecoveryarea.Howcanyoudeletetheflashbacklogsfromthedatabaseifyourdatabaseisupandrunning？（）