anchor.diff:    The file exports two classes and two constants. The `Address` 
     and `Hero` classes define the application _data model_. 
     The `heroes` and `states` constants supply the test data. 
  +  
  +  这个文件导出两个类和两个常量。`Address`和`Hero`类定义应用的*数据模型*。
  +  `heroes`和`states`常量提供测试数据。
   
   .l-main-section
   a#create-component
   :marked
     ## Create a _reactive forms_ component
  +  
  +  ## 创建*响应式表单*组件
  +  
     Make a new file called 
     `hero-detail.component.ts` in the `app` directory and import these symbols:
  +  
  +  在`app`目录下创建一个名叫`hero-detail.component.ts`的新文件，并且导入下列符号：
   
   +makeExample('reactive-forms/ts/src/app/hero-detail-1.component.ts', 'imports','src/app/hero-detail.component.ts')(format=".")
   
   :marked
     Now enter the `@Component` decorator that specifies the `HeroDetailComponent` metadata:
  +  
  +  然后输入这个`@Component`来为`HeroDetailComponent`指定元数据：
   
   +makeExample('reactive-forms/ts/src/app/hero-detail.component.ts', 'metadata','src/app/hero-detail.component.ts (excerpt)')(format=".")
   
  
positive.code: a#formgroup
  :marked
    ## Add a FormGroup
    Usually, if you have multiple *FormControls*, you'll want to register 
    them within a parent `FormGroup`.
    This is simple to do. To add a `FormGroup`, add it to the imports section 
    of `hero-detail.component.ts`:
  
  +makeExample('reactive-forms/ts/src/app/hero-detail-2.component.ts', 'imports','src/app/hero-detail.component.ts')(format=".")
  
  :marked
    In the class, wrap the `FormControl` in a `FormGroup` called `heroForm` as follows:
  
  +makeExample('reactive-forms/ts/src/app/hero-detail-2.component.ts', 'v2','src/app/hero-detail.component.ts')(format=".")
  
  :marked
    Now that you've made changes in the class, they need to be reflected in the 
    template. Update `hero-detail.component.html` by replacing it with the following.
  
  +makeExample('reactive-forms/ts/src/app/hero-detail-2.component.html', 'basic-form','src/app/hero-detail.component.html')(format=".")
  
  
negative.code:   Notice that now the single input is in a `form` element. The `novalidate` 
    attribute in the `<form>` element prevents the browser 
    from attempting native HTML validations. 
    
    注意，现在单行输入框位于一个`form`元素中。`<form>`元素上的`novalidate`属性会阻止浏览器使用原生HTML中的表单验证器。
  
    `formGroup` is a reactive form directive that takes an existing 
    `FormGroup` instance and associates it with an HTML element. 
  