现行小学数学教材中,梯形与平行四边形的的概念分别是:只有一组对边平行的四边形叫做梯形,两组对边分别平行的四边形叫平行四边形。从上述概念可知,平行四边形与梯形是四边形中相互独立互不包容的两个概念。但两个概念仔细一对比,发现平行四边 The current primary mathematics textbooks, trapezoidal and parallelogram concept is that: only a group of parallel to the side of the quadrangle is called the trapezoid, two pairs of parallel sides of the parallelogram called the parallelogram. It can be seen from the above concept that the parallelogram and the trapezoid are two concepts that are independent of each other in the quadrangle. However, a careful comparison of the two concepts, found parallel to four sides