单项选择题
Which type of backup must be performed first with an incremental backup？（）
A. Level 1 B. Level 0 C. Level 2 D. Level 3
单项选择题 Whichtypeofbackupbacksuponlydatablocksmodifiedsincethemostrecentbackupatthesamelevelorlower？（）
单项选择题 Whichisthecorrectcommandtobackupthedatabase，backupthearchivedredologs，andthenremovethebacked-uparchivedredologs？（）
单项选择题 Compressedbackupsworkwithwhichofthefollowingcommands？（）
