They're definitely not expecting more than two, and even if you do give more than two, from my understanding of the marking scheme it's pretty counter productive. I remember it being like say it was a question that required 2 reasons, and you gave three instead; 2 correct, 1 wrong. In this case, you'll still only get 1 mark out of the 2 because one of your reasons was wrong. Same goes for if you gave 20 examples and 2 were wrong, then you'll get zero. I'm pretty sure it works like this, otherwise it would be quite easy to bullshit your way through an exam...On another note, many of the 'very good student responses' are pretty horrible from what I've seen in terms of wordiness so don't rely on them too much. There's much better ways to phrase your answers.