Which three statements are true regarding the use of the Database Migration Assistant for Unicode(DMU)?（）

• A、A DBA can check specific tables with the DMU
• B、The database to be migrated must be opened read-only.
• C、The release of the database to be converted can be any release since 9.2.0.8.
• D、The DMU can report columns that are too long in the converted characterset.
• E、The DMU can report columns that are not represented in the converted characterset.