第四部分重点介绍真实销售制度。
迄今 国家执行的是期房销售制度，就是先付款再交房的方式。
What heretofore country carries out is system of period room sale, pay to make the way of the room again first namely.
另一方面，卖方通过销售制度的设计，可以减少买方的“搭便车”行为；
While buyers' behavior is subjected to its own factors, sellers can reduce free riding through designation of distribution systems.
应用推荐