The design of Attendance Assistant class diagram

The above is the class Diagram 1.0 version, where the "academic teacher" and "mailbox" the relationship between the dispute is greater, but from the call relationship analysis I think this design is not wrong, so this problem we finally agreed. As for the connection between the student and the attendance table, I was really ill-conceived, so I should make a change. Then there is a time table should match an attendance table, so the number of combinations of the relationship is wrong, the following is the revised version:

Based on the relationship of the classes that only consider the important logical parts, and the design of the time series diagram, I have further complemented the UML class diagram:

The design of Attendance Assistant class diagram