回複：My small envelope was also lost.

That's address printed on the upper right corner of first page of RFE letter. but I find that that's a general address for I-140. see this link:

http://www.uscis.gov/portal/site/uscis/menuitem.5af9bb95919f35e66f614176543f6d1a/?vgnextoid=c31c5cdc2c463110VgnVCM1000004718190aRCRD&vgnextchannel=fe529c7755cb9010VgnVCM10000045f3d6a1RCRD

I will use FedEX to mail it, so I paln to mail it to

USCIS Nebraska Service Center
850 S St.
Lincoln, NE 68508-1225

Anybody have comments?

Thanks.