YourdatabaseisinARCHIVELOGmode.OnFridayevening，youperformanonlinedatabasebackupbyusingtheBACKUPDATABASEcommandattheRecoveryManager（RMAN）promptandclosethe

database.OnMonday，theSystemAdministratorinformsyouaboutthefailureoftwoharddisks.Oneofthelostdiskscontainstwodatafiles，HR1.DBFandHR2.DBF，bothofwhichbelongtoaread/writetablespacenamedHR.Thediskalsocontainsadatafile，USERS.DBF，whichbelongstoaread/writetablespacenamedUSERS.YouneedtorestoreandrecoverthedatabasebackupthatwasperformedonFridayevening.Aftermountingthedatabase，youissuethefollowingRMANcommands： RMAN＞RESTOREDATABASE； RMAN＞RECOVERDATABASE； AftersuccessfullyexecutingtheseRMANcommands，youissuethefollowingstatementusingSQL*Plus： SQL＞ALTERDATABASEOPEN； Youreceivethefollowingerrorswhenattemptingtoopenthedatabase： ORA-01157：cannotidentify/lockdatafile10seeDBWRtracefile ORA-01110：datafile10：’D：\USERS.DBF’ Whatisthecauseoftheseerrors？（）