Really bad app poor performance
Have many bugs, no customer services
APP本身难用
内容不错，但是APP本身太难用了……购买课程后，根本无法加载出来，折腾到课程进行了40分钟还是不行。请开发者修正一下问题！！！
Unstable and poor performance
Some functions showed empty page. The login is not user friendly as only mobile phone number of Mainland China is accepted. International emails such as gmail are rejected. The app is unstable and usually gives no response to user inputs. There is a huge room for improvements.
