7o-o72006-06-15 15:24:00
根据USCIS官方网站说明:

Rights:

To be employed in the United States at any legal work of your qualification and choosing.

文中没有提到换工作的限制.

网址:
http://www.uscis.gov/graphics/howdoi/PermRes.htm

另外,这里有一个讨论:
http://www.immigrationportal.com/showthread.php?t=214143
7o-o72006-06-15 15:31:03
这里有一个值得注意的回复:30-90天