Identify three valid methods of opening, pluggable databases (PDBs).（）

• A、ALTER PLUGGABLE DATABASE OPEN ALL ISSUED from the root
• B、ALTER PLUGGABLE DATABASE OPEN ALL ISSUED from a pdb
• C、ALTER PLUGGABLE DATABASE PDB OPEN issued from the seed
• D、ALTER DATABASE PDB OPEN issued from the root
• E、ALTER DATABASE OPEN issued from that pdb 
• F、ALTER PLUGGABLE DATABASE PDB OPEN issued from another pdb
• G、ALTER PLUGGABLE DATABASE OPEN issued from that pdb