再問

現在需要遞交864 和NVC要求的其他文件。864表需要寄到Chicago，
-Who told you the I-864 needs to be sent to Chicago in your case?

That's based on the instruction for I-864.  There is link to 'where to file' to https://www.uscis.gov/i-864?.   It says to mail to Chicago.

但是NVC的各種表格可以email遞交，是嗎？
-NVC should have sent you the instructions, right? Just follow the NVC Instructions to submit these documents.
Read this website for some information:
https://travel.state.gov/content/travel/en/us-visas/immigrate/the-immigrant-visa-process.html

Based on NVC instruction, there is a checklist.  It says below.  So the Signed Affidavit of Support is I-864?  it did not mention the form specifically.  多謝！

3. Signed Affidavit of Support(s).................... [ ] [ ] [ ]

        Proof of U.S. Status.............................. [ ] [ ] [ ]

       Proof of Domicile................................. [ ] [ ] [ ]

      Petitioner's Civil Documents................. [ ] [ ] [ ]

      ........................