How to find the privileges and roles granted to a user in Oracle?

I am using Linux, Oracle10g. I have created one user called test. and granted create session and select any dictionary permission to the same user.

i also granted sysdba and sysoper roles to the same users.

Now i want to display all the privileges and roles granted to the user. I found following query but it shows only create session and select dictionary privileges.

select privilege 
from dba_sys_privs 
where grantee='SAMPLE' 
order by 1;

please help to resolve the issue.

Thanks