单项选择题
A.Undo data becomes obsolete after 1，000 seconds.
B.Undo data gets refreshed after 1，000 seconds.
C.Undo data will be stored permanently after 1，000 seconds.
D.Committed undo data would be retained for 1，000 seconds if free undo space is available.
E.Undo data will be retained in the UNDOtablespacefor 1，000 seconds， then it gets movedmovedto the TEMPORARYtablespaceto provide read consistency.
单项选择题 YourCertkiller.comdatabaseisinARCHIVELOGmode.ThedatafilethatbelongstotheSYSTEMtablespacehasbecomecorrupted.Uptowhatpointcanyourecoverthedatabase？（）
单项选择题 You work as a database administrator for Certkiller .com. In your production database， the size of Database Buffer Cache needs to be increased immediately for the current as well as future instances of the database. The Oracle instance has been configured to accommodate any changes in the size of the memory structures. At this is production database， you want to accomplish this task with no impact on the user’s connections. Which activity must you have completed before accomplishing this task？（）
多项选择题 You work as a database administrator for Certkiller .com. You decided to manage client and server connections using Local Naming method in Certkiller .com. When you try to connect to the database you get the following error： ERROR： ORA-12154：TNS：couldnot resolve service name Which network configuration files would you look into to resolve this error？（）