May I ask, we take off from Melbourne to Shenzhen at 9 am on the 5th, and arrive in Shenzhen at 4 pm on the 5th or 6th? The ticket doesn't show an extra day, so it should be 4 pm on the 5th, right? I feel that Australia is three hours ahead of us ?

Flights are usually shown in local time.

Fly for ten hours

Arrival time is local time. When flying back to domestic from Australia, the time difference has already been reflected in the flight time.

It must be in the afternoon of the 5th.