8 大师，您好。
多谢您指教，我父母绿卡办得非常顺利。他们过几天要来美国住几天。这是他们的移民签证获批准之后第一次入境。妈妈问我入境的时候有什么要注意的。 我真的不知道啊。我去social security office 问过了。他们说爸妈入境后3周内SSN 卡片会寄到家。绿卡的事情他们不知道。
我现在知道的就是广州签证处给了他们俩袋子资料。他们也没弄懂这是干什么的。我已经嘱咐他们一定要带着了。
想请教您，他们过海关的时候有什么需要准备的吗？
-Nothing special, but they can not open the sealed envelop the visa officer gave to them! They need to provide that sealed envelop to the CBP officer at the port of entry when they enter US.
绿卡是当时得还是以后邮寄到家里？
-Have you paid the immigant fee yet? If yes, then the green card will be mailed to them (your home address in US) after they enter US in about one month. If not yet, you had better pay the fee now, and send the receipt to your parents, and they can provide the receipt to the CBP officer when they enter US.
See these links for immigtant fee payment:
https://www.uscis.gov/file-online/uscis-immigrant-fee
https://www.uscis.gov/tools/how-do-i-customer-guides/how-do-i-pay-uscis-immigrant-fee
