请教8老师：
1。父母在美国申请绿卡，同时也申请Advanced Parole Document。7月11日收到Notice of Action, 说是批准了。Your travel document will be mailed to you separately. 现在已7月31日，还没收到。不知一般多久能收到？
-Call USCIS to verify the approval and ask whether it was mailed out or not.
2。因为8月上旬他们有事回国。已经批准，但还没拿到Advanced Parole Document情况下，他们可以回国吗？
-Yes, they can if it was really approved. But there is risk if it wasn't really approved (it was a mistake) or it gets lost in the mail during it is sent to your US address.
