I booked a flight number 8 from Harbin to Nantong, but later the flight was cancelled and I changed it to the 11th.

Generally not. You can only change your booking on the same route.
Yes, but policies are changing at any time during the epidemic. Please consult the airport or airline for details.
Generally not. You can only change your booking on the same route.
Yes, but policies are changing at any time during the epidemic. Please consult the airport or airline for details.