3、一个字典里存放一些居民的姓名和年龄，编程找到年龄最大的人并输出。 person1={"li":18,"wang":50,"zhang":20,"sun":22}

好的，这是一个简单的Python代码实现：

person = {"li": 18, "wang": 50, "zhang": 20, "sun": 22}
max_age = max(person.values())
for name, age in person.items():
    if age == max_age:
        print(f"The oldest person is {name}, {age} years old.")
        break

运行结果为：

The oldest person is wang, 50 years old.