Oracle Database Discussions

hi, experts,
I am a newbie of oracle database.

I study oracle database using Oracle Database 10g Express Edition Release 10.2.0.1.0
I have created 2 users, TESTING and TESTING2
I have created a table SKU for TESTING (the owner of table SKU is TESTING)
I set the GRANTS of table SKU.

please see this image : http://img694.imageshack.us/img694/3433/questionl.png

I have a created a synonym for TESTING2

please see this image : http://img197.imageshack.us/img197/2064/question2.png

then I use sqldeveloper , login as TESTING2 and run this query.
SELECT * FROM S_SKU;

the results are returned.

I have found that the results can be returned regardless of the value of GRANTABLE of the GRANT.

what are the "grantable" for?

thank you very much!