多项选择题
A.By multiplexing the control files
B.By multiplexing the redo log files
C.By decreasing the size of redo log files
D.By configuring mean time to recover （MTTR） to a lower value
E.By setting the UNDO_RETENTION parameter to a higher value
单项选择题 You work as a database administrator for Supportcenter.cn. Users in the Supportcenter.cn PROD database complain about the slow response of transactions. While investigating the reason you find that the transactions are waiting for the undo segments to be available， and undo retention has been set to zero. What would you do to overcome this problem？（）
单项选择题 InyourSupportcenter.cndatabaseservertheparameterPLSQL_CODE_TYPEhasbeensettoNATIVE.Whichobjectwouldbeachievedbythesetting？（）
单项选择题 YouworkasadatabaseadministratorforSupportcenter.cn.OnaMondaymorning，youfindthedatabaseinstanceaborted.Afterinspectingthealertlogfile，youexecutetheSTARTUPcommandinSQL*Plustobringtheinstanceup.Whatstatementistrue？（）