你好8老师
目前有绿卡，想回国长待，不知道该入籍还是拿着绿卡和回美证往返跑？ 据说回美证最多能用5年2+2+1 是么？
-There is no limit on how many times you can renew it, but you cannot abuse this benefits, so if you apply for renewal too many time, USCIS will not approve it. Normally two to three times should be OK.
