I followed the instruction on the following link:
http://blog.wenxuecity.com/blogview.php?date=200706&postID=42162#EAD765
EAD 材料清单如下：
Form I-765
Copy of I-485 Receipt Notice － 仅单独提交的免费 EAD 申请
Copy of Last EAD (front and back) － 没有的话用护照 copy 代替
Copy of Approval Notice of EAD Application (Denial notice if applicable)
Two 2" x 2" photos (name & A# on back in pencil)
新版的 I-765 有下列变动：交费的 EAD 不再需要 I-485 收据， I-485 的 EAD 不再需要 I-94 了.
It turned out that they sent back my application package with the notice which checked category G: "We were unable to systems verify that you have a Form I-485, Application for Adjustment Status, on file. .... Please resubmit your application and applicable fees along with proof of your earlier filing of your form I-485."
By the way, I did submit all required documents and $340 check except I-485 notice copy. I guess that there was no new version of I-765 without requiring I-485 copy. In the future, we better submit everything to INS for EAD application.
Anyway, I still appreciate pjiang's blog. I have learned a lot from his posts. Merry Christmas and Happy new year to everyone in this forum!