Oracle 12c – How can I recover a dropped table?

I'm using Oracle 12c Standard Edition.

I accidentally drop the table and try to recover it, but the table does not appear in Recyclebin.

I think the tablespace is due to SYSTEM.

Create table test (
aaa varchar2 (20)
....
)
SISTEMA TABLESPACE
STORAGE
NEXT 1024K
)
/

Thank you!