婆婆来美国满五个月（B-2）时我们为她申请六个月的延期。过了三个月后，USCIS来信要我们补充材料：
1.submit evidence to establish that you have a residence aboard to which you intend to return.
2.submit documentary evidence that you have the ability to financially maintain yourself throughout duration of your stay.
3.have your sponsor submit a statement of support specifying contribution he will make on your behalf, room board, living expense, medical expense, etc.
#1 是房产证，#2是银行存款证明，#3该如何准备？请过来人指教！谢谢！
Merry Christmas and happy new year!