053-218

Your database is running in ARCHIVELOG mode. You are performing a user-managed backup of the DATA1 tablespace. You place the DATA1 tablespace in backup mode by issuing the following statement:
ALTER TABLESPACE data1 BEGIN BACKUP;
While you are performing the backup, an error occurs that causes the instance to terminate abnormally.
Which statement about the DATA1 tablespace is true?
A. The DATA1 tablespace is automatically taken out of backup mode when the instance aborts.
B. If you restart the database, the DATA1 tablespace will be automatically taken out of backup mode when the database is opened.
C. If you restart the database, the DATA1 tablespace will be automatically taken out of backup mode when the database is mounted.
D. If you restart the database, the database will not be opened.

backup mode不能启动数据库，Alter tablespace data1 end backup;alter databse end backup;
　　此题考点是手动管理的备份恢复。当你忘记结束备份模式时，才开库的时候由于是异常终止，需要实例恢复，会一直在不一致的状态无法 open。此时应该在 mout 状态手动执行 end backup 命令，再 alter databaseopen 数据库。
　　注意：不要在任何从备份重建的备份上使用 alter database end backup。你需要对这些数据文件运行recover 命令，然后对那些确保是当前的数据文件执行 end backup 命令。