YOU CAN DO
select tablespace_name from dba_tablespaces where status ='READ ONLY';
select status from dba_tablespaces where tablespace_name ='YOURTBS';
STATUS COLUMN IN DBA_TABLESPACES FLAG FOR ONLINE,OFFLINE,READ ONLY.
HOPE THIS HELPS
Life is what is happening today while you were planning tomorrow.
you know that I first told him to look status column?
and he came back saying it's online or offline then it simply means that he only saw online/offline, in other words he has NO read-only tablespaces so I said how can you check for read-only tablespaces if you dont have any?