实现学生登录和教师登录，学生可以选择课程，查看课程分数和个人信息等。教师可以查看自己的课程和所有课程信息，查看学生所选课程，录入学生分数等功能。(Realize student login and teacher login. Students can select courses, view course scores and personal information, etc. Teachers can view their own courses and all course inform