题目内容

静止液体内部压力与其表面压力无关。

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Yourdatabasehasexperiencedalossofdatafileusers_01.dbf，whichisassociatedwithaablespacecalledUSERS.
Thedatabaseisstillrunning.
Whichanswerproperlydescribestherderofthestepsthatyouwouldusetorecoverfromthiserror？（）
a. Shutdownthedatabase.
b.Taketheusers_01.dbfdatafileofflinewiththealterdatabasecommand.
c.Restoretheusers_01.dbfdatafilefrombackupmediawiththerequiredarchivedredologs.
d.Restorealluserstablespace-relateddatafilesfrombackupmedia.
e.Issuetherecovertablespaceuserscommand.
f.Issuetherecoverdatafileusers_01.dbfcommand.
g.Startupthedatabase.
h.Bringtheusers_01.dbfdatafileonlinewiththealterdatabasecommand.

离心泵的泵壳既是汇集叶轮抛出液体的部件，又是流体机械能的转换装置。

离心泵的扬程是液体出泵和进泵的压强差换算成的液柱高度。

离心泵铭牌上注明的性能参数是轴功率最大时的性能。