回复：回复：请看左边皮匠大师的文章，专门谈这个问题。

You are a very logical person and should be a good scientist if you work in science areas.

My statement you concerned about means you can not use your old I-140 sponsored by your old employer to file your I-485 if you no more work for this employer.

But if this employer does not withdraw the I-140, and you will come back to work for him later, possiblly you can still use this I-140 for your I-485 filing. The question is you must convince USCIS to believe your intent to work for your GC sponsor.