有些比例问题条件比较隐蔽，数量关系复杂，用一般方法解答比较困难。若能采用“统一不变量”的方法进行分析，不仅过程简单，而且容易理解和掌握。现举例如下：一、统一份数和例１甲、乙两班的同学人数相等，各有一些同学参加课外天文小组。甲班参加天文小组的人数是乙班没有 In some cases, the conditions are rather subtle and the quantity is complex. It is difficult to solve the problem in a general manner. If you can use the “unified invariant” method of analysis, not only the process is simple, but also easy to understand and grasp. Now for example as follows: First, the unified copies and cases 1 Class A, B classmates equal number of students, each with some students to participate in extracurricular astronomy team. The number of teams in the Astronomy Teams participating in astronomical teams is not in Class B