苏科版八年级下册第十一章《图形与证明(一)》学习了命题的概念,用命题形式给出一个数学问题,要判断它是错误的,只要列举一个满足命题的条件但结论不成立的例子,就足以否定这个命题,这样的例子就是通常意义下的反例。在初中教学中,反例的构建是教学中一种非常重要的教学手段和方式。反例教 Su Ke version of the eighth grade under the eleventh chapter “graphics and proof (a)” learned the concept of proposition, propositional form to give a mathematical problem, to judge it is wrong, as long as a list of conditions to meet the proposition but the conclusion An example that is not valid is enough to deny the proposition. An example of this is the counter-example in the usual sense. In junior high school teaching, the construction of counterexamples is a very important teaching method and method in teaching. Anti-instance teaching