我持加拿大TN签证，在美国工作，有博士学位，怎么申请美国绿卡？
-Two ways: 1. you sponsor yourself (i.e., self sponsored) using EB1A or NIW category;
2. Ask your employer to sponsor you using EB1B, EB2, or EB3 category.
需要多少时间？
-Hard to say. the time on different category is different.
请介绍有经验的律师，谢谢！
