dba priviledges

I granted some people DBA priviledges but I just realized that, I want them to do everything with the exception of modify a table. What is the best thing to do in order for them to do everything but not to modify a table?

You could do something like:

-- Create a role

$ sqlplus system/manager
SQL> create role user_role;

-- Grant all the necessary the previliges to this role
SQL> grant select, insert, update, delete on emp to user_role;

-- Grant this role to the users
SQL> grant user_role to scott;


Hope this helps!

When you say "modify a table" do you mean insert,update, delete data? If so:
1. create role READONLY;
2. grant select any table to READONLY;
3. grant READONLY to userA;

If you mean don't let the users modify the structure of the table, but allow them to change any of the data then:
1. create role USE_ALL_TABLES;
2. grant select any table to USE_ALL_TABLES;
3. grant insert any table to USE_ALL_TABLES;
4. grant delete any table to USE_ALL_TABLES;
5. grant update any table to USE_ALL_TABLES;
6. grant USE_ALL_TABLES to userA;