H-1B 已经6年， 是否只要有 批过的 I140（原雇主不会取消的），H-1B就可以每次 RENEW 延3年。
-Yes.
如果，这期间，有 H1->H4 的短暂经历， 然后 找到新雇主， 还可以从 H4 转到 H1, 并有 3年的 H-1B吗？
-Yes if you have had the experience of H1 extension beyond the 6 years limit, i.g. you extended your H1 to the 8th year, but laid off at the 7th, then changed to h4 and then find a job, thus you have no problem to change your H4 to h1 at 3 years interval.
Another situation is that: if you change your h1 to h4,F1, etc. before your H1 reaches the 6 years limit, you can change your h4, etc. and extend your h1 beyond the 6 year limit after you find a job.
