c – 多重继承和指针实现

namespace Example1 {

class A {
public:
    A() {}
    virtual ~A() {}
private:
    float data_A;
};

class B {
public:
    B() {}
    virtual ~B() {}
protected:
    float data_B;
};

class Derived : public A,public B {
public:
    Derived() {}
    virtual ~Derived() {}
protected:
    float data_Derived;
};

}

int main (void)
{
using namespace Example1;
B* pb = new Derived;
delete pb;
}

pb现在应该指向Derived对象的B部分.
但派生对象也派生自A,意味着它有一个子对象..而且一个子对象应该是“第一”,因为派生类首先从A继承.

编译器如何批准？为了使其正常工作,它添加了什么？

而且,删除对象时如何正确释放内存？