You have to shut down the database instance with the ABORT option because of a hardware failure. Which statement is true about the subsequent opening of the database？（）

多项选择题WhichtwooperationscanbeflashedbackusingtheFlashbacktechnology？（）

A.DROP USER SMITH；
B.DROP TABLE EMPLOYEES；
C.DROP TABLESPACE USERS；
D.ALTER TABLE SALES_REP DROP PARTITION P1；
E.ALTER TABLE EMPLOYEES DROP COLUMN DESIG_ID；

多项选择题View this parameter setting in your database：   DB_CREATE_FILE_DEST=’D：  oracle product 10.2.0 oradata oracle’  You created a tablespace by using this command：   CREATE TABLESPACE USERS；  Which two statements are true about the USERS tablespace？（）

A.The tablespace has two data files.
B.An error is reported and tablespace creation fails.
C.Data files are created with names generated by the instance.
D.The tablespace can be extended without specifying the data file.
E.Data files belonging to the USERS tablespace cannot be renamed.

单项选择题Your database is in NOARCHIVELOG mode and a logswitch happens every 20 minutes. On Thursday morning，media failure resulted in corruption of a data file belonging to the TOOLS tablespace. Backups are taken on every Sunday.  What would you do in this situation？（）

A.recover using Oracle Flashback Database technology
B.restore the data files from backup and perform a complete recovery
C.restore only the corrupted data file and perform tablespace recovery
D.restore the data files from backup and perform cancel-based recovery
E.restore the entire database from the most recent backup and start the instance and open the database

单项选择题Your database is running under automatic undo management and the UNDO_RETENTION parameter is set to 900 sec. You executed the following command to enable retention guarantee： SQL> ALTER TABLESPACE undotbs1 RETENTION GUARANTEE； What effect would this statement have on the database？（）

A.The extents in undo tablespace retain data until the next full database backup.
B.The extents containing committed data in the undo tablespace are never overwritten.
C.The extents which no longer contain uncommitted data in the undo tablespace are not overwritten for at least15 minutes.
D.The extents containing committed data in the undo tablespace are not overwritten until the instance is shut down.

单项选择题WhichstatementistruewhenyouruntheSQLTuningAdvisorwithlimitedscope？（）

A.Access path analysis is not performed for the SQL statements.
B.SQL structure analysis is not performed for the SQL statements.
C.SQL Profile recommendations are not generated for the SQL statements.
D.The staleness and absence of the statistics are not checked for the objects in the query supplied to the SQL Tuning Advisor.