anchor.diff:    It takes two arguments: the component type to override (`HeroDetailComponent`) and an override metadata object.
     The [overide metadata object](#metadata-override-object) is a generic defined as follows:
   
  -  它接受两个参数：要替换的组件类型(`HeroDetailComponent`)和用于替换的元数据对象。
  -  [替换元数据对象](#metadata-override-object)是泛型类，就像这样：
  +  它接受两个参数：要重载的组件类型(`HeroDetailComponent`)和用于重载的元数据对象。
  +  [重载元数据对象](#metadata-override-object)是泛型类，就像这样：
   
   code-example(format="." language="javascript").
     type MetadataOverride<T> = {
  
positive.code: :marked
    # Override component providers
  
    # 替换组件提供商
  
    The `HeroDetailComponent` provides its own `HeroDetailService`.
  
  
negative.code: :marked
    ### More overrides
  
    ### 更多重载
  
    The `TestBed.overrideComponent` method can be called multiple times for the same or different components.
    The `TestBed` offers similar `overrideDirective`, `overrideModule`, and `overridePipe` methods
    for digging into and replacing parts of these other classes.
    
    `TestBed.overrideComponent`方法可以在相同或不同的组件中被反复调用。
    `TestBed`还提供了类似的`overrideDirective`、`overrideModule`和`overridePipe`方法，用来深入并重载这些其它类的部件。
  
    Explore the options and combinations on your own.
  
  