单项选择题 You experienced a loss of data files in your database. You did not lose any of your control files. You are going to use RMAN to restore and recover the database. Currently， your instance is shut down.  Which sequence of commands is correct to restore and recover your database？（）

多项选择题 You received this error message because Oracle Net Services cannot locate the connect descriptor specified in the tnsnames.ora configuration file：   ORA_12154： TNS：could not resolve service name Which three actions would be appropriate in helping to resolve the error？（）

单项选择题 You have used the CROSSCHECK BACKUP command to verify that the backups recorded in the RMAN repository actually exist.  Which command should you now use to check if any of the files were missing？（）