题目内容

在传热实验中用饱和水蒸汽加热空气，总传热系数K接近于空气侧的对流传热系数，而壁温接近于饱和水蒸汽侧流体的温度值。

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在列管式换热器中，当热流体为饱和蒸汽时，流体的逆流平均温差和并流平均温差相等。

YouworkasadatabaseadministratorforCertkiller.com.UsersintheCertkillerPRODdatabasecomplainabouttheslowresponsewhenaccessingthedatabase.IntheActiveSessionWaiting：Configurationpageyoufindthatthemajorityofthewaittimeisfortheredologbuffer.FurtherinvestigationusingtheRunQueuegraphandoperatingsystemtoolsrevealsthattheredologfilesareonthesamedisks，andthatthediskI/Ofortheredologfilesisthereasonfortheperformancedegradation.
Whichtwoactionswouldyoutaketogainperformance？（）

Yousettherecoverywindowtosevendays

YourdatabaseoperatesinARCHIVELOGmode.Theredologfilesarenotmultiplexedandoneoftheonlineredologsismissing.Themissingredologsequence，230，isnotarchivedanditcontainedinformationfrom10：35a.m.onwards.Thecurrenttimeis11：00a.m.Becauseofadiskcrash，youexecutedthefollowingcommandtoperformanincompleterecovery：
RMAN＞RUN{
2＞SETUNTILSEQUENCE230THREAD1；
3＞ALTERDATABASEMOUNT；
4＞RESTOREDATABASE；
5＞RECOVERDATABASE；
6＞ALTERDATABASEOPENRESETLOGS；
7＞}；
Withreferencetothisscenario，whichstatementistrue？（）