单项选择题
A. a list of files that require a backup within three days
B. a list of files that have not been backed up for three days
C. a list of files that RMAN recommends be backed up only once in every three days， based on low volatility
D. a list of files for which a backup has already been performed and may need a backup after three days
单项选择题 Youhavespecifiedthewarningandcriticalthresholdvaluesofanapplicationtablespacetobe60%and70%respectively.Fromthetablespacespaceusagemetrics，youfindthattheactualspaceusagehasreachedthespecifiedwarningthresholdvalue，butnoalertshavebeengenerated.Whatcouldbethereasonforthis？（）
多项选择题 YouworkasadatabaseadministratoratCertkiller.com.Inyourproductiondatabase，youobservethatusers’transactionsareconsumingalotofresourceandyouplantoimposeresourcerestrictionsbyusingResourceManager.ForwhichthreeresourcescanyouenableusagerestrictionsbyusingResourceManager？（）
单项选择题 Whichstatementcorrectlydescribesthechangetrackingwriter（CTWR）backgroundprocess？（）