单项选择题
A.DROP USER SMITH；
B.DROP TABLE EMPLOYEES；
C.DROP TABLESPACE USERS；
D.ALTER TABLE SALES_REP DROP PARTITION P1；
E.ALTER TABLE EMPLOYEES DROP COLUMN DESIG_ID；
单项选择题 Yourdatabaseishavingtwocontrolfiles，threeredologfilegroupswithtwomembersineachgroup.Failureofwhichfilewouldcauseaninstancetoshutdown？（）
单项选择题 Youhavebeenrecentlyhiredasadatabaseadministrator.YourseniormanagerasksyoutostudytheproductiondatabaseserverandsubmitareportonthesettingsdonebythepreviousDBA.Whileobservingtheserversettings，youfindthatthefollowingparameterhasbeensetintheparameterfileofthedatabase：REMOTE_OS_AUTHENT=TRUEWhatcouldhavebeenthereasontosetthisparameterasTRUE？（）
单项选择题 Your database is open and users are connected using the LISTENER listener. The new DBA of the system stops the listener by using the following command： LSNRCTL> STOP What would happen to the sessions that are presently connected to the database instance？（）