回复：非常感谢8老师！接着问个问题

那如果申请请假条的话，最长在国内可以呆多久？

-Do you mean the 请假条 is the reentry permit? If so, it allows the green card holder to sty outside US for less than two years.

申请请假条期间，人必须在美国吗？

-Yes.

另外， 在帮爸妈申请绿卡的时候没有申请工卡， 如果是看小孩报税合法吗？

-No, it is illegal for them to work. But if they stay in US for > 6 months with you in 2011, they may be considered as your dependents for your tax deduction.

如果现在补交756表是否要另外收费？

-No.

 再次感谢8老师一路以来的热心帮助！