为自己加油

Which four are true about duplicating a database using Recovery Manager (RMAN)? (Choose four.)

A.Duplication can be done by having the auxiliary database instance pull backup sets from the target database instance.
B.A connection to an auxiliary instance is always required.
C.A subset of the target database can be duplicated.
D.A new DBID is always created for the duplicated database.
E.A connection to the recovery catalog instance is always required.
F.A backup of the target database is always required.
G.Duplication can be done by having the target database instance push copies to the auxiliary database instance.
H.A connection to the target database instance is always required.