基类和派生类的一道题，帮我看一下错在哪里？

#include<iostream>
#include<cstring>
using namespace std;
class Vehicle                        //汽车类定义
{
private:
    int Speed;
    int Weight;
public:
    Vehicle(int speed,int weight)
    {
        Speed=speed;
        Weight=weight;
        cout<<"Vehicle类的构造函数被调用"<<endl;
    }
    ~Vehicle()
    {
        cout<<"Vehicle类的析构函数被调用"<<endl;
    }
    void Display()
    {
        cout<<"最大速度："<<Speed<<"km/h"<<'\t'<<"车的重量："<<Weight<<"kilo"<<'\t'<<endl;
    }
    int GetSpeed()
    {
        return Speed;
    }
    int GetWeight()
    {
        return Weight;
    }
};
class Truck:public Vehicle           //卡车类定义（公有继承）
{
private:
    int Load;
public:
    Truck(int load,int speed,int weight):Vehicle(speed,weight)
    {
        Load=load;
        cout<<"Truck类的构造函数被调用"<<endl;
    }
    ~Truck()
    {
        cout<<"Truck类的析构函数被调用"<<endl;
    }
    void DisplayTruc()
    {
        cout<<"载重："<<Load<<"kilo"<<'\t';
        Display();
    }
    int GetLoad()
    {
        return Load;
    }
    double ratio()
    {
        double ratio;
        int load,weight;
        load=GetLoad();
        weight=GetWeight();
        ratio=load/(load+weight);
        return(ratio);
    }
};
int main()
{
    Truck truck1(500,160,500);
    truck1.DisplayTruc();
    cout<<"卡车的载重效率="<<truck1.ratio()<<endl;
    return 0;
}

请问输出载重效率的错在哪了？