当一个企业的生产功能取决于另一个企业或消费者的选择时，就会发生生产外部性。例如：苹果园和蜜蜂。总所周知，外部性会导致帕累托效率低下，如何解决生产外部性问题？
Production externality occurs when a firm's production function depends on choices of another firm or consumer.Example:apple orchard and honeybees.As we all konw,the externality may cause Pareto inefficiency. How to solve the production externality?