code:

public String Perform(IVerb verb, INoun actor, String verb_preposition = null)
{
    //if a method Verb exists on the derived noun class, call it.
    MethodInfo method = this.GetType().GetMethod(CultureInfo.CurrentCulture.TextInfo.ToTitleCase(verb.Name.ToLower()), new [] {typeof(INoun), typeof(String)});
    Object[] parameters = new Object[] { actor, verb_preposition };
    if (method != null)
    {
        return (string)method.Invoke(this, parameters);
    }
    else
    {
        return String.Format("Action not defined: Noun {0}, Verb {1}\r\n", Name, verb.Name);
    }
}