public void PickQuestion()
{
if (currentQuestionAndAnswer != null)
throw new InvalidOperationException ("question is not empty, can't start new one");
currentQuestionAndAnswer = this.randomizer.GetRandomUnsuccessItem ();
if (currentQuestionAndAnswer == null)
throw new InvalidOperationException ("no avalible questions for you");
}
public void Clear()
{
currentQuestionAndAnswer = null;
}