python代码不理解、从Car开始不理解

Question

class Vehicle:
    def __init__(self, speed):
        self.speed = speed

    def drive(self, distance):
        print 'need %f hour(s)' % (distance / self.speed)

class Bike(Vehicle):#开始执行
    pass

class Car(Vehicle):
    def __init__(self, speed, fuel):
        Vehicle.__init__(self, speed)
        self.fuel = fuel

    def drive(self, distance):
        Vehicle.drive(self, distance)
        print 'need %f fuels' % (distance * self.fuel)

b = Bike(15.0)
c = Car(80.0,1.12)
c.drive(200.0)

Answer 1

class Car(Vehicle):表示声明一个car类，并且这个car类继承了Vehicle这个父类后面的是重写了父类的两个方法。b = Bike(15.0)   //这里实例化一个Bike类并（赋值speed =15.0）c = Car(80.0,1.12) //这里实例化一个Bike类并（赋值speed = 80.0 ,fuel=1.12）c.drive(200.0)//调用 drive方法

Answer 2

class Car(Vehicle) 表示Car类继承与Vehicle类