1.添加学生：输入学生信息，将输入的学生的信息保存到all_students中

all_students = [
{'name':'stu1', 'age': 19, 'score':81, 'tel':'192222'},
{'name':'stu2', 'age': 29, 'score':90, 'tel':'211222'},
{'name':'stu3', 'age': 12, 'score':67, 'tel':'521114'},
{'name':'stu4', 'age': 30, 'score':45, 'tel':'900012'},]
new_name = input('姓名：')
new_age = input('年龄：')
new_score = input('成绩：')
new_tel = input('电话：')
new_student = {'name':new_name, 'age':new_age ,'score':new_score, 'tel':new_tel}
all_students.append(new_student)
print(all_students)

2.按姓名查看学生信息：

all_students = [
{'name':'stu1', 'age': 19, 'score':81, 'tel':'192222'},
{'name':'stu2', 'age': 29, 'score':90, 'tel':'211222'},
{'name':'stu3', 'age': 12, 'score':67, 'tel':'521114'},
{'name':'stu4', 'age': 30, 'score':45, 'tel':'900012'},]
new_name = input('姓名：')
for studet in all_students:
    if studet['name'] == new_name:
        print(studet)

3.求所有学生的平均成绩和平均年龄

 all_students = [
    {'name':'stu1', 'age': 19, 'score':81, 'tel':'192222'},
    {'name':'stu2', 'age': 29, 'score':90, 'tel':'211222'},
    {'name':'stu3', 'age': 12, 'score':67, 'tel':'521114'},
    {'name':'stu4', 'age': 30, 'score':45, 'tel':'900012'},]
    sum_score = 0
    sum_age =0
    for student in all_students:
        sum_score += student['score']
        sum_age += student['age']
    print('平均成绩:',sum_score / len(all_students) , '平均年龄:',sum_age / len(all_students))

4.删除班级中年龄小于18岁的学生

all_students = [
    {'name':'stu1', 'age': 19, 'score':81, 'tel':'192222'},
    {'name':'stu2', 'age': 29, 'score':90, 'tel':'211222'},
    {'name':'stu3', 'age': 12, 'score':67, 'tel':'521114'},
    {'name':'stu4', 'age': 30, 'score':45, 'tel':'900012'},]
index = 0
for student in all_students:
    index += 1
    if student['age'] < 18:
        del all_students[index-1]
print(all_students)

5.统计班级中不及格的学生的人数

all_students = [
    {'name':'stu1', 'age': 19, 'score':81, 'tel':'192222'},
    {'name':'stu2', 'age': 29, 'score':90, 'tel':'211222'},
    {'name':'stu3', 'age': 12, 'score':67, 'tel':'521114'},
    {'name':'stu4', 'age': 30, 'score':45, 'tel':'900012'},]
index = 0
for student in all_students:
    if student['score'] < 60:
        index += 1
print(index)

6.打印手机号最后一位是2的学生的姓名

all_students = [
    {'name':'stu1', 'age': 19, 'score':81, 'tel':'192222'},
    {'name':'stu2', 'age': 29, 'score':90, 'tel':'211222'},
    {'name':'stu3', 'age': 12, 'score':67, 'tel':'521114'},
    {'name':'stu4', 'age': 30, 'score':45, 'tel':'900012'},]
index = 0
for student in all_students:
    if student['tel'][-1] == '2':
        print(student['name'])