俺上麵說的沒錯。狗了一個來，你自己看吧。

http://help.cbp.gov/cgi-bin/customs.cfg/php/enduser/std_adp.php?p_faqid=572&p_created=1048279878&p_sid=wX-*G4Wi&p_accessibility=0&p_redirect=&p_lva=&p_sp=cF9zcmNoPTEmcF9zb3J0X2J5PSZwX2dyaWRzb3J0PSZwX3Jvd19*****nQ9MjExLDIxMSZwX3Byb2RzPTAmcF9jYXRzPTAmcF9wdj0mcF9jdj0mcF9zZWFyY2hfdHlwZT1hbnN3ZXJzLnNlYXJjaF9ubCZwX3BhZ2U9MSZwX3NlYXJjaF90ZXh0PXBlcm1hbmVudCByZXNpZGVudHM*&p_li=&p_topview=1


Foreign nationals that are lawful permanent residents of the U.S. must present a Permanent Resident Card (“Green Card”, INS Form I-551), a Reentry Permit (if gone for more than 1 year), or a Returning Resident Visa (if gone for 2 years or more) to reenter the United States. U.S. LPRs are not required by the U.S. to have a passport for travel, although most foreign destinations will require you to have one to enter their country. (LPRs that are out of the U.S. for more than 180 days are subject to new immigrant inspection procedures as per 8 USC 1101.)