设计Student、Course和Teacher类

以下是Python代码实现：

class Student:
    def __init__(self, name, id):
        self.name = name
        self.id = id
        self.courses = []
    
    def enroll(self, course):
        self.courses.append(course)
    
    def drop(self, course):
        self.courses.remove(course)
    
    def list_courses(self):
        print(f"{self.name}'s courses:")
        for course in self.courses:
            print(course.name)
    
class Course:
    def __init__(self, name, teacher):
        self.name = name
        self.teacher = teacher
        self.students = []
    
    def add_student(self, student):
        self.students.append(student)
        student.enroll(self)
    
    def remove_student(self, student):
        self.students.remove(student)
        student.drop(self)
    
    def list_students(self):
        print(f"Students enrolled in {self.name}:")
        for student in self.students:
            print(student.name)
    
class Teacher:
    def __init__(self, name, id):
        self.name = name
        self.id = id
        self.courses = []
    
    def add_course(self, course):
        self.courses.append(course)
    
    def remove_course(self, course):
        self.courses.remove(course)
    
    def list_courses(self):
        print(f"{self.name}'s courses:")
        for course in self.courses:
            print(course.name)

使用示例：

# 创建学生、课程和教师实例
alice = Student("Alice", 1)
bob = Student("Bob", 2)
math = Course("Math", Teacher("Mr. Smith", 101))
english = Course("English", Teacher("Mrs. Johnson", 102))
mr_jones = Teacher("Mr. Jones", 103)

# 学生选课
math.add_student(alice)
math.add_student(bob)
english.add_student(alice)

# 教师管理课程
mr_jones.add_course(math)
mr_jones.add_course(english)

# 列出学生和课程信息
alice.list_courses() # Alice's courses: Math, English
bob.list_courses() # Bob's courses: Math
math.list_students() # Students enrolled in Math: Alice, Bob
english.list_students() # Students enrolled in English: Alice
mr_jones.list_courses() # Mr. Jones's courses: Math, English

# 学生退课
math.remove_student(bob)
bob.list_courses() # Bob's courses: 
math.list_students() # Students enrolled in Math: Alice