How many times have you been on a conference call for work or in a meeting with a large group of people and all of a sudden your boss asks you a question? Normally, you know the answer and immediately give it. If you are well prepared and know your job inside and out, it should be an easy task. Other times, you might get caught off guard and stumble around for the answer. In this situation, you obviously are not prepared for the meeting at hand and probably shouldn't be pretending to know what is going on.
Did you ever have one of those book study conductors that always deviated from the questions in the book? You know the one. He would ask a question related to the material, but it was asked in his own words. If he was real ballsy, he would call on you to answer if you appeared to be paying attention. Do you remember how hard it was to come up with an answer that wasn't printed in the book? You were so afraid that your answer wouldn't be Society Approved and that he would ding you on it in front of everyone.
On the other hand, if you had a conductor who liked to come up with his own questions but not voluntarily call on someone, most jw's would just sit there looking down with their brains in overdrive trying to scan the paragraph looking for the answer(hint - it probably wasn't there). It would get so quiet and after about 15 seconds of silence and him scanning the room looking for a raised hand, he would just say the answer he was looking for.
I think it's so funny that jw's are supposed to be the most biblically educated people in the world, but yet most cannot think quick on their feet when a simple question is thrown at them. If it's not in black and white and published by the WTS, the answer doesn't exist.