example.cs

public interface IWorkable
{
    void Work();
}

public interface IFeedable
{
    void Eat();
}

public interface IEmployee : IFeedable, IWorkable
{
}

public class Human : IEmployee
{
    public void Work()
    {
        // ....working
    }

    public void Eat()
    {
        //.... eating in lunch break
    }
}

// robot can only work
public class Robot : IWorkable
{
    public void Work()
    {
        // ....working
    }
}