设计一个学生类student,

包括姓名和三门课程成绩，

利用重载运算符”+“将所有学生的成绩相加放在一个对象中，

再对该对象求各门课程的平均分-Design a student class student, including name and three course score, the use of overloaded operator "+"　will add up the results of all students placed in an object, and then demand that the object of various courses of the average