性质定理和判定定理是学习平行四边形的重点，必须认真学好．那么，怎样学习平行四边形的性质定理和判定定理呢？一、掌握条件，把握结论，严格区别定理的条件和结论定理的条件和结论见下表：注意平行四边形的定义既是性质，又是判定方法．二、理解定理的作用，掌握证题方法性? The property theorem and decision theorem are the focus of learning parallelograms and must be carefully studied. So, how can we learn the properties of the parallelogram and the theorem? First, grasp the conditions, grasp the conclusions, the conditions of the strict difference theorem and the conditions and conclusions of the conclusion theorem are shown in the following table: Note that the definition of a parallelogram is both a property and a decision method. Second, to understand the role of the theorem, to grasp the methodological nature of the test?