初学平行线的判定与性质,不少同学常常将它们混淆.因此,我们必须弄清“判定”与“性质”的区别.平行线的“判定”,是在已知某些条件下,用这些条件去判断两条直线平行.我们已经知道,已知下列三个条件之一,就可以判断两条直线平行,这三个条件是:①同位角相等;②内错角相等;③同旁内角互补.当然还可以用平行公理的一个推论进行判定. The judging and nature of the beginner parallel lines are often confused by many students. Therefore, we must make clear the difference between “judgment” and “nature.” The “judgment” of parallel lines is to use these under certain known conditions. Conditions to determine the two straight lines. We already know that one of the following three conditions is known, we can determine the two straight lines, these three conditions are: 1 equal to the same angle; 2 within the wrong angle; 3 with the side angle Complementarity, of course, can also be determined using a corollary of axioms of parallelism.