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.