1.我的綠卡12月過期，我應該提前半年還是90天申請，我看移民局的網站也沒說清楚。因為I-90有一個選項是：my existing green card has already expired or will expire within 6 months.
-You can file I-90 in advance up to 6 months before your green card expires.
2. 我可以離開美國，在12月之前回來嗎？
-Yes.
還是我要申請新綠卡拿到stamp才可以離開美國-If you file I-90 before your green card expires, your green card will be extended for one year when you conduct the biometrics (talk to the IO at that time).
