回複：這種長期中國工作，1）還能維持H1嗎？

2) 或者是不是用不著維持H1，
-Correct. If you want to get the H1 status in the future, your employer just file the petition and get it approved, and then you just apply for the H1 visa to come back.
而用B1、2來往美中出差？
-It is hard to get the B visa due to the immigration intent (I-140 filing). So, you may have a problem for short visiting US.

3）排期到時交485是不是隻能在廣州交？
-You have to come back to US to file I-485 when the PD is current. Of course, you can choose to get the immigration visa in Guangzhou using consular processing instead of filing I-485 within US.
Up to you.

4）綠卡批後，可以一直在海外為美國公司工作而保持綠卡？
-You need to get reentry permit to stay/work outside US for a maximum of two years and pay the tax to US IRS even if you work outside US after you get the GC.

另外，
我朋友在A公司I140剛批，但有獵頭想挖他去B公司海外分公司
做高管，B公司同意辦綠卡，可是該怎麽申請呢？
-The I-140 sponsored by A will be invalid, and the B has to do it all over again for him. But he can use thePD from the approved I-140 from A.

如果B公司隻能先花1年給他辦完I140再派他到海外去，時間太長了。。
-He can work outside US and then, Company B can file the PERM/I-140 for him later/anytime.

謝謝。