编写程序声明一个Vehicle基类，有Run，Stop两个虚成员函数，由此类派生出Bicycle类，Motorcar类，从Bicycle和Motorcar派生出摩托车Motorcycle类，它们都覆盖改写了从基类继承过来的Run，Stop函数。在main函数中对上述内容进行多态测试。

下面是一个简单的实现：

#include <iostream>
using namespace std;

class Vehicle {
public:
    virtual void Run() {
        cout << "Vehicle is running." << endl;
    }
    virtual void Stop() {
        cout << "Vehicle is stopped." << endl;
    }
};

class Bicycle : public Vehicle {
public:
    void Run() {
        cout << "Bicycle is running." << endl;
    }
    void Stop() {
        cout << "Bicycle is stopped." << endl;
    }
};

class Motorcar : public Vehicle {
public:
    void Run() {
        cout << "Motorcar is running." << endl;
    }
    void Stop() {
        cout << "Motorcar is stopped." << endl;
    }
};

class Motorcycle : public Bicycle, public Motorcar {
public:
    void Run() {
        cout << "Motorcycle is running." << endl;
    }
    void Stop() {
        cout << "Motorcycle is stopped." << endl;
    }
};

int main() {
    Vehicle* v1 = new Bicycle();
    v1->Run(); //输出 Bicycle is running.
    v1->Stop(); //输出 Bicycle is stopped.
    
    Vehicle* v2 = new Motorcar();
    v2->Run(); //输出 Motorcar is running.
    v2->Stop(); //输出 Motorcar is stopped.
    
    Vehicle* v3 = new Motorcycle();
    v3->Run(); //输出 Motorcycle is running.
    v3->Stop(); //输出 Motorcycle is stopped.
    
    delete v1;
    delete v2;
    delete v3;
    return 0;
}

在上述代码中，我们首先声明了一个`Vehicle`基类，其中包含了`Run()`和`Stop()`两个虚成员函数。然后我们从`Vehicle`派生出了`Bicycle`和`Motorcar`两个类，并且在这两个派生类中分别覆盖了`Run()`和`Stop()`函数。接着我们又从`Bicycle`和`Motorcar`这两个类派生出了`Motorcycle`类，并且在`Motorcycle`类中同样覆盖了`Run()`和`Stop()`函数。最后在`main()`函数中，我们对上述类进行多态测试。

我们分别声明了指向`Bicycle`、`Motorcar`和`Motorcycle`对象的指针，并且分别调用了它们的`Run()`和`Stop()`函数。由于这些函数都是虚函数，所以在运行时会根据对象的实际类型来调用相应的函数，从而实现了多态的效果。