谢谢8老师的帮助！我朋友还有几个问题想请教你：
SB-1 和国内绿卡申请不同?是否主要优点是不需要等排期?
-SB-1 is faster, and It is green card reinstatement (i.e. recovery of the green card validity).
By the way, there is no 排期 for a US citizen's parent to apply for green card.
如果放弃绿卡申请旅游签证，是否有父母，一个放弃绿卡申请旅游签证，另一个持有绿卡的成功案例，
-I don't see this kind of case yet. But normally it should not be difficult to get the B2 visa after abandoning the green card even if the spouse is the green card holder. Problem is that you need to have the reason to convince the VO that you will return to China after the short visiting US. If you cannot get the B2 visa after giving up the green card, you may apply for the immigrant visa in China.
还是只有父母都放弃绿卡申请旅游签证的案例?
谢谢！
