I didn't do MMI format when I interviewed way back when, but the best advice I have for vet school interviews in general is that remember their goal - it isn't necessarily to test your knowledge to its full extent, but to test your ability to think on your feet, communicate clearly, and most importantly, stay calm and stick by your answers. There may be some questions designed specifically to make you nervous, defensive, or uncomfortable - they aren't doing it to be mean, they are doing it in order to test out how you might respond in stressful situations, whether they be related to dealing with difficult clients, how to defend your position when questioned, etc. It's ok if you can't answer everything. Don't cry and fuss and freak out. Admit it, be calm, cool, and collected and move on. Don't guess what the "right" answer is or that answer they "want" - give *your* answer and stick by it. I would argue that staying pleasant and professional is more important than exactly which answer you give to each question or scenario.