C++问题，请教一下大家

设计两个类 汽车类 属性：颜色，品牌，车轮个数 行为：行驶
修车厂类 属性：名称，地址 行为：修车
描述逻辑：汽车可以行驶，一旦汽车损害（轮胎爆胎，某个轮子不可用），可送至修理厂维修，修好后可正常行驶

#include<iostream>
#include<string>

using namespace std;

class Car {
    string color;
    string brand;
    int wheelNum;
public:
    Car(string c,string b,int n):color(c),brand(b),wheelNum(n){}

    void drive(){
        cout<<"The "<<color<<" "<<brand<<" car is driving."<<endl;
    }

    void breakdown(int num){
        cout<<"The "<<num<<"th wheel of the "<<color<<" "<<brand<<" car is broken."<<endl;
        this->wheelNum--;
    }

    bool isBroken(){
        return (this->wheelNum<=0);
    }
};

class RepairShop{
     string name;
     string address;
 public:
     RepairShop(string n,string a):name(n),address(a){}

     void repair(Car& car){
         cout<<"Repairing the "<<car.color<<" "<<car.brand<<" car..."<<endl;
         //repair process
         car.drive();
     }   
};

int main(){
    Car myCar("red","BMW",4);
    myCar.drive();
    myCar.breakdown(2);

    if(myCar.isBroken()){
        RepairShop myRepairShop("AutoRepair","5th Ave, NY");
        myRepairShop.repair(myCar);
    }

    return 0;
}