母亲已经拿到移民美国的IR5签证，但是签证有效期太短，我无法回中国接她。如何申请签证延期？
-She may contact the US Consulate in Guangzhou and make an appointment to see whether the US Consulate can change her visa expiration date or issue a new visa to her. Explain why she can not land in US on time.
有被拒的风险是多少？！
