您的代码有几个问题：您尚未创建实例：mycar = Car(year, make, speed)

您已将mycar重命名为my_car：即my_car.brake()

类属性称为self.__speed，而不是self.speed。(加速、制动和获取速度方法)class Car:

def __init__(self, year, make, speed):

self.__year_model = year

self.__make = make

self.__speed = 0

def set_year_model(self, year):

self.__year_model = year

def set_make(self, make):

self.__make = make

def set_speed(self, speed):

self.__speed = 0

def get_year_model(self):

return self.__year_model

def get_make(self):

return self.__make

def get_speed(self):

return self.__speed

#methods

def accelerate(self):

self.__speed +=5

def brake(self):

self.__speed -=5

def get_speed(self):

return self.__speed

def main():

year = input('Enter the car year: ')

make = input('Enter the car make: ')

speed = 0

mycar = Car(year, make, speed)

#Accelerate 5 times

mycar.accelerate()

print('The current speed is: ', mycar.get_speed())

mycar.accelerate()

print('The current speed is: ', mycar.get_speed())

mycar.accelerate()

print('The current speed is: ', mycar.get_speed())

mycar.accelerate()

print('The current speed is: ', mycar.get_speed())

mycar.accelerate()

print('The current speed is: ', mycar.get_speed())

#Brake 5 times

mycar.brake()

print('The current speed after brake is: ', mycar.get_speed())

mycar.brake()

print('The current speed after brake is: ', mycar.get_speed())

mycar.brake()

print('The current speed after brake is: ', mycar.get_speed())

mycar.brake()

print('The current speed after brake is: ', mycar.get_speed())

mycar.brake()

print('The current speed after brake is: ', mycar.get_speed())

#Call the main function

main()