I485 材料如何包装？

My I-140 NIW is pending. I will go to China soon, Can I let other people I-485 petition for me while I am in China? Should I physically in U.S. when sumitting I-485 petition? I really do not want miss this chance, other wise I have to hold until i am back from China, I wish I still can doI-485 when I am back from China next month. Thanks alot for yourhelps.I learned alot from here.