python保留两位小数

请问这个为什么报错啊，。？！……得劲儿竞技等级我就睡觉
😪时间段

{:.2f} 要用引号括起来

• 这个问题的回答你可以参考下: https://ask.csdn.net/questions/764717
• 我还给你找了一篇非常好的博客，你可以看看是否有帮助，链接：python解决亲密数问题，超级简单。
• 除此之外, 这篇博客: Python经典高频率面试问答题汇总！内附答案！中的 48、 什么是断言？应用场景是什么？ 部分也许能够解决你的问题, 你可以仔细阅读以下内容或跳转源博客中阅读:
  

• assert 是的作用？断言
  条件成立（布尔值为True）则继续往下，否则跑出异常，一般用于：满足某个条件之后，才能执行，否则应该跑出异常。
  
  写API的时候，继承GenericAPIView
  
  class GenericAPIView(views.APIView):
                      """
                      Base class for all other generic views.
                      """
                      # You'll need to either set these attributes,
                      # or override `get_queryset()`/`get_serializer_class()`.
                      # If you are overriding a view method, it is important that you call
                      # `get_queryset()` instead of accessing the `queryset` property directly,
                      # as `queryset` will get evaluated only once, and those results are cached
                      # for all subsequent requests.
                      queryset = None
                      serializer_class = None
  
                      # If you want to use object lookups other than pk, set 'lookup_field'.
                      # For more complex lookup requirements override `get_object()`.
                      lookup_field = 'pk'
                      lookup_url_kwarg = None
  
                      # The filter backend classes to use for queryset filtering
                      filter_backends = api_settings.DEFAULT_FILTER_BACKENDS
  
                      # The style to use for queryset pagination.
                      pagination_class = api_settings.DEFAULT_PAGINATION_CLASS
  
                      def get_queryset(self):
  
                          assert self.queryset is not None, (
                              "'%s' should either include a `queryset` attribute, "
                              "or override the `get_queryset()` method."
                              % self.__class__.__name__
                          )
  
                          queryset = self.queryset
                          if isinstance(queryset, QuerySet):
                              # Ensure queryset is re-evaluated on each request.
                              queryset = queryset.all()
                          return queryset
  

• 您还可以看一下 黄勇老师的Python从入门到实战 基础入门视频教程（讲解超细致）课程中的 子类不能继承父类的私有···小节, 巩固相关知识点