http://www.uscis.gov/citizenship/learners/study-test
http://www.uscis.gov/citizenship/quiz/learners/study-test/study-materials-civics-test/naturalization-self-test-1
Google "父母申请绿卡" and you find a lot of information.
• Thanks a lot! -redwest- ♀ (0 bytes) () 12/07/2014 postreply 21:34:23