You are managing an Oracle Database 11g database. You configured the database to run inARCHIVELOG mode.  Which two statements are true in this scenario（）

• A、You must shut down the database instance to perform the backups.
• B、You must configure the Flash Recovery Area （FRA） for the database.
• C、You can perform complete database backups without closing the database.
• D、All the previous closed database backups including control files become invalid after you configure thedatabase to ARCHIVELOG mode.