单项选择题 In which situation will you run the script containing the following statement？（）   CREATE CONTROLFILE REUSE DATABASE SALES NORESETLOGS ARCHIVELOG        MAXLOGFILES 20        MAXLOGMEMBERS 3        MAXDATAFILES 30        MAXINSTANCES 10        MAXLOGHISTORY 1200        LOGFILE        GROUP 1 （   ’/disk1/prod/orders/db/log1a.dbf’，        ’/disk2/prod/orders/db/log1b.dbf’        ）SIZE 100K        GROUP 2 （   ’/disk1/prod/orders/db/log2a.dbf’，        ’/disk2/prod/orders/db/log2b.dbf’        ） SIZE 100K，        DATAFILE   ’/disk1/prod/orders/db/database1.dbf’，                                           ’/disk2/prod/orders/db/file1.dbf ’；

多项选择题 You are the Database Administrator （DBA） of your company. You execute the following statement on an Oracle 10g instance：   SQL> ALTER SYSTEM SWITCH LOGFILE；   Which two tasks are performed when the statement is executed？ （）

单项选择题 You are maintaining the SALES database of TeleStar Corporation. The online redo log configuration of the database is as follows：   One of the redo log members， redo3b， is lost due to disk failure.   How will you recover the redo log member redo3b？（）