我看官方网站上是这么说的：
Have continuous residence in the United States as a green card holder for at least 5 years immediately preceding the date of filing the application 。
Be physically present in the United States for at least 30 months out of the 5 years immediately preceding the date of filing the application。
第一条说5年都要在美国，第二条又说物理上30个月以上。
我妈妈拿了绿卡，她要是每年在美国住6个月，中国住6个月。5年后能申请公民吗？
-Yes, but if she goes forth and back between China and US too often, the IO at the port of entry may give her trouble. The green card is for her to stay in US permanently, not for her to use it as border-crossing card.
多谢！
Have continuous residence in the United States as a green card holder for at least 5 years immediately preceding the date of filing the application 。
Be physically present in the United States for at least 30 months out of the 5 years immediately preceding the date of filing the application。
第一条说5年都要在美国，第二条又说物理上30个月以上。
我妈妈拿了绿卡，她要是每年在美国住6个月，中国住6个月。5年后能申请公民吗？
-Yes, but if she goes forth and back between China and US too often, the IO at the port of entry may give her trouble. The green card is for her to stay in US permanently, not for her to use it as border-crossing card.
多谢！
