回複：謝謝863211！情況是這樣的，

朋友長期在中國，有綠卡。每半年要來美國呆幾天，所以上次來申請了二年的 白皮書，之後又專門來美打指紋，打完指紋就回中國了。白皮書批下來寄到我家。我給她把白皮書經郵局寄回去，寄了快一個月了還沒收到，估計丟掉了。我去郵局查，郵局的人告訴我國際的priority mail無法跟蹤，我無法向朋友交代啊。以前我往國內寄同樣的信從沒丟過，我真後悔沒掛號。沒臉見朋友了。
-Your friend can return to US to file I-131 using her green card. But if your friend has stayed in China for > one year continuously, she can not use the green card to enter US to file I-131 for a new reentry permit application. In this case,, she needs to apply for the SB-1 visa to come back. See this website for SB-1 visa:
http://travel.state.gov/visa/immigrants/info/info_1333.html