To accomplish user-managed backup for the USERS tablespace, you issued the following command to put the database in backup mode:
SQL> ALTER TABLESPACE users BEGIN BACKUP;
While copying the file to the backup destination a power outage caused the instance to te minate abnormally.
Which statement is true about the next database startup and the USERS tablespace?
A. The database will open, and the tablespace automatically comes out of the backup mode.
B. The database will be mounted, and recovery must be performed on the USERS tablespace.
C. The database will be mounted, and data files in the USERS tablespace must be taken out of the
backup mode.
D. The database will not be mounted, and you must restore all the data files for the USERS tablespace from the backup, and perform recovery.
原文：http://www.cnblogs.com/Babylon/p/7839495.html