数学中真命题的正确性可以由条件通过推理来加以证实,而假命题的证明只需举一个反例即可.尤其是几何命题,举一个反例,胜过千言万语.但有些假命题的反例难以构造,本文通过实例,介绍借助圆规构造常见假命题反例的方法,供读者参考. The correctness of true propositions in mathematics can be verified by reasoning through reasoning, whereas the proof of false propositions need only be a counterexample. In particular, geometric propositions can be cited as a counter-example, which is better than a thousand words. However, some counter-examples of false propositions Difficult to construct, this article through examples, introduced with compasses to construct counter-examples of common false propositions for readers reference.