父母年纪八十多，父亲得过肝癌，有绿卡，想在国内待一年以上，是不是可以申请延期？入境会有麻烦吗
-Do you mean they have green card? If yes, then they need to file I-131 application for reentry permit which allows them to stay in China for > one year < two years. After they conduct the biometrics, they can leave US (not need to wait for the reentry permit approval). Then, you can send the reetry permit to them after it is approved.
