今天看到博客园一篇文章写抽象类实例化，net framework是ms的，我改不了abstract。但是抽象类是可以做出实例化效果的。为了增强记忆，把代码抄一遍吧！
protected sealed override Delegate CombineImp(Delegate follow)
{
if(base.GetType()!=follow.GetType())
{
throw new Exception();
}
Delegate delegate2=(MulticastDelegate)((MulticastDelegate)follow).MemberwiseClone();
Delegate delegate3=delegate2;
while(delegate2._prev!=null)
{
delegate2._prev=(MulticastDelegate)delegate2._prev.MemberwiseClone();
delegate2=delegate2._prev;
}
delegate2._prev=this;
return delegate3;
}