绿卡更新已经半年前递交的，除了收到移民局的一封常规回执信，现在还没有收到新卡，现在更新绿卡通常需要多长时间？
-Normally one to two years, case by case.
在等待新卡期间能否申请公民？
-Yes. Provide the copy of the expired green card and the I-90 receipt.
申请公民自己就可以办还是需要请律师？
-It is very simple procedure, not need lawyer. Read this website carefully and watch the video there and follow the N-400 Instructions to file N-400 online or by paper:
Application for Naturalization | USCIS
