As an invigilator for many years, I can only tell you that there is a spare draft paper, but if this important national exam is held, only one draft paper will be given to everyone at first. If it is used up, you can raise your hand and send it to the second draft paper in the case of recycling the last draft paper. Under special circumstances, such as the first draft paper has important draft paper contents, two draft papers can be temporarily held at the same time, but both draft papers must be recycled when handing in the papers. You ask whether the second draft paper can be used up for a third one after recycling, and so on, but you can only guarantee that there is only one draft paper on your desktop at a time, and under special circumstances, there can be no more than two. You must write a name on the draft paper, and you can't lose a corner when you recycle it. Why is there such a rule? Just think about why you can't bring your own draft paper and write the answer on the admission ticket.