You are not really expected to come up with answers on the spot in a debate. You are supposed to do research on the topic before the debate. For example, if your debate is on abortion do some research on the topic and pick a side in the issue to defend. You must know all viewpoints on the issue to be a good debater. For example, you need to know your arguments and also what they will likely argue. That way you can counter their arguments and beat them. You can do it man!