多项选择题 Your database is running in ARCHIVELOG mode. One of the data files， USERDATA01.dbf， in the USERS tablespace is damaged and you need to recover the file until the point of failure. The backup for the datafile is available.  Which three files would be used in the user-managed recovery process performed by the database administrator （DBA）？（）

单项选择题 You work with a newly created database. Presently， there is no application load on the database instance. You want to create a baseline for tuning the application， so you decide to collect recommendations that can be implemented to improve application performance.  What action must you take to achieve this？（）

单项选择题 Youneedtomaintainarecordofalltransactionsonsometablesforatleastthreeyears.Automaticundomanagementisenabledforthedatabase.Whatmustyoudoaccomplishthistask？（）