多项选择题
A.You cannot export data from a remote database.
B.You can rename tables during an import operation.
C.You can overwrite existing dump files during an export operation.
D.You can compress the data during export but not the metadata because it is not supported
多项选择题 Whichstatementsaretrueaboutcheckpointing（）
多项选择题 After performing a clean shut down of the database instance for maintenance， you mount the database andthen execute a command to open the database：SQL> ALTER DATABASE OPEN； Which two statements are true（）
单项选择题 InwhichsituationistheUNDO_RETENTIONparameterbeignored，evenifitissettoavalue（）