IReaderWriter.cs

public class A
{
	public void F1(){}
}

public class B : A
{
	public void F2(){}
}

public class C : B
{
	public void F3(){}
}

public interface IReaderWriter<TEntity>
{
	TEntity Read();
	void Write(TEntity entity);
}

public class ReaderWriter<TEntity> : IReaderWriter<TEntity> where TEntity : new()
{
	public TEntity Read()
	{
		return new TEntity();
	}

	public void Write(TEntity entity)
	{
	}
}