1. System problem. There is a fault or bug in the evaluation system itself, which makes it impossible to calculate or refresh the total learning time. Contact the relevant personnel or technical support of Tianjin Construction Education and Training Center, feedback the problems and fix them.

2, network problems, the total study time can not be updated because the network connection is unstable or disconnected, you can try to change the network environment, such as using other Wi-Fi or mobile data networks.