On March 3 19, I found out why my space-time partner called on March 3 1.

It is usually a short message notification, which may be missed.

Spatio-temporal companion refers to the person who stays with the diagnosed patient for 14 days in the same spatio-temporal grid. Usually, the detection range is 800 meters by 800 meters, and * * * stays for 10 minute.

The infected person has been to a place within 14 days, and the trajectory of you 14 days intersects with him. Whether it is a physical brush or a drift in communication signals, it may be considered as a problem of time and space. For those who are judged as time and space companions, they will generally receive SMS reminders from the Public Security Bureau and the Municipal Center for Disease Control and Prevention.