条件求值问题就是题目已给定了一些量的具体值,或者量之间的关系,而求其它有关量或式的值的问题．解方程的问题,也可以说是一种广义的条件求值．这种问题的关键就是合理、恰当地妙用条件,当然这种妙用一方面是用题目中的显性条件,更重要地也要挖 The conditional evaluation problem is that the problem has given a certain amount of specific values, or the relationship between quantities, and finds other problems related to the value of the quantity or formula. The problem of solving equations can also be described as a generalized conditional evaluation. The key to this kind of problem is to use reasonable and appropriate magical conditions. Of course, this kind of magical use is based on explicit conditions in the subject and more importantly,