Which three statements are true concerning the multitenant architecture?（）

A. Each pluggable database (PDB) has its own set of background processes.
B. A PDB can have a private temp tablespace.
C. PDBs can share the sysaux tablespace.
D. Log switches occur only at the multitenant container database (CDB) level.
E. Different PDBs can have different default block sizes.
F. PDBs share a common system tablespace.
G. Instance recovery is always performed at the CDB level.