老师您好！
感谢您之前解答了我的很多问题！我的485 Pending, 现在收到RFE要求Supplement J. 原文要求如下：
"The record establishes that you are the Principal Applicant of an Employment-Based For I-485. In order to continuje processing of your case, you must submit a properly completed and signed Supplement J, Confirmation of Bona Fide Job Offer or Request for Job Portability Under INA Section 204(j), showing that the offer of intended permanent employment as stated in the Form I-140 continues to exist or that you intend to port to a new offer of employment in the same or similar occupational classification as the job specified in the underlying Form I-140."
我的情况是一直在同一个公司工作，EB2 I-140。后来想降级到EB3, 但是Approved I-140还是EB2。所以我有两个EB2 I-140。我的485是用第一个I-140申请的。I-485 pending已经8个月。
请教老师：
1. 这个RFE只要求我交Form Supplement J 是吗？我还要交其他证明材料（e.g. Employment Verification Letter）吗？
2. 我要选择哪一项: "1a. Confirm that the job offered to you in the Form I-140, that is the basis of your Form I-485, remains a bona fide job offer you intend to accept once your Form I-485 is approved." 还是"1b. Request job portability under INA section 204(j) to a new, full-time, permanent job offer that you intend to accept once your Form I-485 is approved."？我没有换工作，也没打算换公司。
3. 可以叫律师帮我交这个Form Supplement J 和其他需要的材料吗？
4. 我收到RFE，是因为交I-485时没有交Supplement J，还是因为我有两个EB2 I-140？
5. How do I know whether USCIS has received the RFE documents I responded or not？
非常感谢老师辛苦解答！