替朋友求问8老师：
朋友申请父母绿卡已经批下来，visa要求6月份入境，现在有实际问题：
1, 第一次落地签，在等正式绿卡期间的几个月，返回加拿大等绿卡是否合法（加拿大国籍）？
-Yes. After they enter US using the immigrant visa, they become green card holders immediately. The IO will stamp/endorsed the visa at the port of entry which is qual to the temporary green card valid for one year. So, they can use this endorsed visa to travel out of US any time before they receive the plastic green card. But they had better not stay outside US for more than 6 months continuously.
2，如果合法，是不是从入境开始不超过180天？还是登完陆返回加拿大时开始算？
3，朋友有一个未成年的妹妹，如果父母为妹妹在美国申请绿卡，父母是否必须在美国有工作和至少有多少收入？-Not have to. But your friend needs to be the joint sponsor to provide the financial support if the parents have no income.
银行存款是否可以作为收入？
首先谢谢8老师能回答，也谢谢有经验的网友不吝赐教。
所有人猪年幸福，恭喜发财。
