No wonder you have no idea about it--it is most likely in your employer's hands now. Most employer hold the original copy, which is required by U.S. Embassy in China for your H4 (or H1B) petition. Ask your spouse to talk to his or her employer and "borrow" it and promise to return it when you are back. Good luck. (I'm just finished preparing my H1B documentation for visa revalidation in China.)