help please, if anyone knew or met this situation before, thank

my 485 was approved yesterday, today LP received this email from CIS:

On November 29, 2007, we mailed a notice requesting additional evidence
and/or information in this case. Please follow the instructions on the
notice to submit the evidence and/or information requested. This case
will be held in suspense until we either receive the evidence or the
opportunity to submit it expires. Once you submit the information and/or
evidence requested, you will be notified by mail when a decision is
made, or if the office needs something further from you. If you move while this case is pending, call customer service.

I want to know, normally what kind of additional evdience it requests, and how long need to respond it?( because she is in China now, using AP)

if anyone knew this situation, or anyone had the same situation before, please give your ideas, thank you very much!!!