读罢贵刊2000年3期P_(21)的《争鸣》篇,仍觉有争鸣处。 1.对于原问题,在解答之前,是应考虑到利用充要条件来转化。只有这样解答才完美无缺。但由于问题答案的特殊性,利用充分性中的n可求而说明原问题中n的存在性,这没有逻辑错误;当然,如果充分性中的n不 Reading Disputing Articles in the 3rd issue of P_(21) in the 2000 issue of the magazine, you still feel that there is a dispute. 1. Before the answer to the original question, consideration should be given to the use of sufficient and necessary conditions for conversion. Only this solution is perfect. However, due to the particularity of the answer to the question, the use of n in sufficiency can be used to explain the existence of n in the original question. There is no logical error; of course, if n in sufficiency is not