How to implement multiple inheritance in C #

C # How to achieve multiple inheritance, the key is the interface can write the implementation of the method

Namespace Extensions
{
Using System;
Using ExtensionMethodsDemo1;


public static Class Extension
{
Extended interface
public static void MethodB (this imyinterface myinterface)
{
Console.WriteLine ("Extension.methodb (this imyinterface myinterface)");
}
}
}
Namespace ExtensionMethodsDemo1
{
Using System;
Using Extensions;

public interface IMyInterface
{
void MethodB ();
}

Class A:imyinterface
{
public void MethodB () {Console.WriteLine ("A.methodb ()");}
}

Class B:imyinterface
{
public void MethodB () {Console.WriteLine ("B.methodb ()");}

}

Class C:imyinterface
{
public void MethodB () {Console.WriteLine ("C.methodb ()");}

}

Class Extmethoddemo
{
static void Main (string[] args)
{
A A = new A ();
b b = new B ();
c C = new C ();

A.methodb ()
B.methodb ()
C.methodb ()

}
}
}