and come back in 2 months. hopefully, by then, the site won't allow people to post messages as "guest". i found this is a very unique problem with the site, which always discoursages me to join many discussions. it's very hard to keep track of the person who wrote the message and sometimes the same person can post several messages using different identities. so i salute to all of the friends here:
goodbye for now. thank you all very much for the fun and things i've learned from here, especially the founders of the site.