众所周知,数学解题中常用的一种特殊化策略是先研究一般问题的几个特例,从中发现解题途径,进而解决一般问题.这一策略同样适用于构造问题.就构造而言,由于问题的特例相对简单,其构造容易实现,况且特例中的构造有时并不容易直接迁移到一般问题之中,因此,需要对每一个特例穷举所 It is well-known that one specialization strategy commonly used in mathematical problem solving is to study several special cases of general problems and discover the ways to solve the problems so as to solve the general problems. This strategy is also applicable to the construction problems. In terms of the structure, The special case is relatively simple and its construction is easy to implement. Moreover, the construction in the special case sometimes can not easily be directly transferred to the general problem. Therefore,