高三复习中我们发现了不少学生对解析几何中有关求参数范围的问题不知从何入手,他们常常在多个字母面前理不清思路,建立不起关系式(等式或不等式)。其原因主要是学生在扑朔迷离的关系式中找不准问题的实质背景。本文在此介绍几个这类问题的常见背景及 In the review of the third year, we found that many students do not know where to find the parameters in the analytical geometry. They often confuse the ideas in front of multiple letters and cannot establish relationships (equations or inequalities). The main reason for this is the fact that students cannot find out the true background of the problem in the complicated and confusing relationship. This article describes the common background of several such issues and