Some people may ask that when the Pythagorean School initially tried to confirm whether √2 is a rational number, they did not know that √2 is not a rational number. In this case, could you ask: √2 can be written in the form of the simplest fraction? The equivalent statement is, can p and q in √2= p/q be mutually prime? The author's answer is that you can't ask such a question. The reason is that, first of all, such a question is not the question discussed, because the question discussed should be - can p and q in √2= p/q be all integers? Therefore, such questions are unnecessary; Moreover, regardless of the necessity of discussion, we have to ask, since the arguer does not know whether √ 2 is a rational number, how can we ensure that this question will not be a complex question?