桌子上有一只盘子，每次只能放一只水果。爸爸专向盘子中放苹果，妈妈专向盘子中放橘子，一个儿子专等吃盘子中的橘子，一个女儿专等吃盘子中的苹果。用PV操作实现他们之间的同步机制。

这是一个典型的生产者-消费者问题，可以用互斥锁（Mutex）和条件变量（ConditionVariable）来解决。在Python中，可以使用`threading`模块来实现这个场景：

import threading

class FruitBasket:
    def __init__(self):
        self.apple = 'Apple'
        self.orange = 'Orange'
        self.lock = threading.Lock()
        self.condition = threading.Condition(self.lock)
        self.eaten = False

    def put_fruit(self, fruit_type, who):
        with self.lock:
            if fruit_type == self.apple:
                print(f"{who} is putting an apple.")
                self.eaten = False
                self.condition.notify_all()  # Notify all waiting consumers
            elif fruit_type == self.orange:
                print(f"{who} is putting an orange.")
                self.eaten = False
                self.condition.notify_all()

            # If the basket is full (for simplicity, assume only one type of fruit at a time)
            if self.eaten:
                self.condition.wait()  # Wait until someone eats the current fruit

    def eat_fruit(self):
        with self.lock:
            while True:
                if not self.eaten:
                    print(f"Someone eats ({self.apple} if available) and the basket becomes empty.")
                    self.eaten = True
                    break
                else:
                    self.condition.wait()  # Wait until there's a fruit to eat


# Consumers
dad = threading.Thread(target=FruitBasket().eat_fruit, name="Dad")
mom = threading.Thread(target=FruitBasket().eat_fruit, name="Mom")

# Producers
son = threading.Thread(target=FruitBasket().put_fruit, args=("Orange", "Son"), name="Son")
daughter = threading.Thread(target=FruitBasket().put_fruit, args=("Apple", "Daughter"), name="Daughter")

dad.start()
mom.start()
son.start()
daughter.start()

dad.join()
mom.join()
son.join()
daughter.join()

在这个例子中，每个线程分别代表爸爸、妈妈和孩子，他们会通过`put_fruit`和`eat_fruit`方法相互协作。生产者在`put_fruit`函数中放置水果并唤醒等待的消费者，而消费者在`eat_fruit`函数中检查是否有水果，并在有水果时吃掉。通过互斥锁保证同一时间只有一个操作在进行，而条件变量则用于控制何时通知其他线程。