回複：H1-B時效和綠卡申請PD時間問題，見內

1) H1-B 6 years only count the time inside US.
2) I don't think you can come back on old H1-B. H1-B is expired as soon as you left your job.
3) yes, PD is the date file PERM. But you have to working for same company until 1/2 year after I-485. before that, you have to start over. Some company may let you use PD from the previous I-140. PERM can takes years in case of auditing. I-140 is about 4 months.