So I finally got in the mail my final documents that I have to bring for the immigration officer to look over, but I can not reproduce one of the item on the list. Due to the fact my father's US permanent resident card has been taken back because he became an US citizen. He has his certificate of naturalization and passport, but from what he tells me the Hong Kong government is not accepting it for some reason. How do I get proof of the US permanent resident card? I do believe the green card is destroyed once the card has been given back to the US government. Please reply ASAP. Thank you.