dict = {"china":"中国","apple":"苹果","dog":"狗"}
if dict.contains("dog")
{
del = dict.popitem("dog") # 当词条"dog"存在时，才执行删除操作
print("被删除的内容：%\n",del)
print("删除后的字典内容：%\n",dict)
}
else
{
print("%\n","该词条不存在！")
}