模拟：桌上有一只盘子，每次只能放入一个水果。爸爸专向盘子中放苹果，妈妈专向盘子中放桔子，一个女儿专等吃盘子里的苹果，一个儿子专等吃盘子里的桔子。只要盘子空则爸爸或妈妈都可以向盘子放一个水果，仅当盘子中有自己需要的水果时，儿子或女儿可以从盘子中取出水果。(Simulation: there is a plate on the table, only one fruit at a time. Dad put Apple special dishes, special dishes in the mother put an orange, a daughter and only eat the apple on the plate, a son eat dish orange. As long as the plate is empty, the father or mother can put a fruit on the plate, and only when the plate has its own fruit, the son or daughter can take the fruit out of the plate.)