C++多态性:如何测试派生自另一个基类的类?

对标题的措辞表示抱歉,我不知道如何改进。但我的问题是:

#include <iostream>
using namespace std;

class Base {};
class Base2 {};
class C : public Base, public Base2 {};
class D : public Base {};

void isDerivedFromBase2(Base *p) {
    if (...) { /* test whether the "real object" pointed by p is derived from Base2? */
        cout << "true" << endl;
    }
    cout << "false" << endl;
}
int main() {
    Base *pc = new C;
    Base *pd = new D; 
    isDerivedFromBase2(pc); // prints "true"
    isDerivedFromBase2(pd); // prints "false"

    // ... other stuff
}

如何测试由基类指针表示的对象 Base * ,是从另一个基类派生的 Base2 ?