判定命题“一组对边和一组对角相等的四边形是平行四边形”的真假性是学完平行四边形的性质和判定后的一道常见习题,学生解题的错误率很高,教师在教学中通常都作了简单化的处理——画出一个反例的图了事,原因很简单——一个反例足以证明命题的真假,讲评后学生的掌握情况往往也并不理想,2013学年第二学期我区八年级期末考试考了这道题, Judgment proposition “A group of parallel and a group of diagonals equal to the parallelogram” is the true and false nature of the parallelogram and judge after a common problem, the student problem-solving error rate is high, the teacher In teaching are usually made a simplistic treatment - to draw a counter-example of the plot, the reason is very simple - a counterexample sufficient to prove the truth of the proposition, postgraduates grasp the situation is often not ideal, the 2013 school year The second semester of my eighth grade final exam test this question,