You can get here the form https://www.travelchinaguide.com/embassy/pdf/affidavit-of-marital-status.pdf for single status. You need to fill out 2 copies: one copy completed, signed and notarized; the other copy completed and signed only. Both needs to be original, no photocopy. in addition, make sure the name on this form should be the same as the name on your passport.