父母有綠卡，去年在美呆了1年，10月底回中國，本來計劃今年四月底回美，機票都買好了，結果父親最近不小心摔倒，導致骨折手術，遵醫囑可能需要修養半年，到今年下半年才能返美。不知道這樣對他們的綠卡是否有影響？
-They must return to US before their stay in China reaches one year! Just bring the doctor/hospital diagnosis for his injury and treatment, and explain it to the IO at the port of entry if asked.
特此請教8老師和各位大俠，看看這種情況應該如何處理，多謝！！
