近几年一些省市的中考物理压轴题中 ,常常出现一类与“极值问题”有关的命题 .这类题从培养学生的思维能力、运用数学解决物理问题的能力来看均是好题 ,但学生解答这类试题时往往错误百出 ,错误往往是由于解题思维方法上的缺陷而造成的 .1　主观臆断具体表现在 :对问题的性质、 In recent years, a number of propositions related to “extreme-value problems” have appeared in some physical examination topics in the examinations in some provinces and cities. These questions are good questions in terms of cultivating students’ thinking ability and using mathematics to solve physical problems. , But students often have to make mistakes in answering such questions. Errors are often caused by flaws in the way of thinking in the problem. 1 Subjective judgment is specifically expressed in the nature of the problem,