多项选择题
Which two operations require undo data？（）
A.committing a transaction B.rolling back a transaction C.recovering from failed transactions D.recording a transaction to redo log files E.rolling forward during instance recovery
多项选择题 WhichtwostatementsaretrueregardingthedatabaseinARCHIVELOGmode？（）
单项选择题 Becauseofapoweroutage，instancefailurehasoccurred.Fromwhatpointintheredologdoesrecoverybeginandwheredoesitend？（）
单项选择题 WhichstepdoyouneedtoperformtoenableauserwiththeSYSDBAprivilegetologinasSYSDBAiniSQL*Plus？（）
