anchor.diff:  
     `src/app/contact`目录中也有一个新文件`contact-routing.module.ts`。
     它定义了我们前面提到过的`联系人`路由，并提供了`ContactRoutingModule`，就像这样：
  +  
   +makeExample('ngmodule/ts/src/app/contact/contact-routing.module.ts', 'routing', 'src/app/contact/contact-routing.module.ts (routing)')(format='.')
  +
   :marked
     This time you pass the route list to the `forChild` method of the `RouterModule`.
     The route list is only responsible for providing additional routes and is intended for feature modules.
  
positive.code: 
      创建`src/app/core`文件夹
  
    * Move the `UserService` and `TitleComponent` from `src/app/` to `src/app/core`.
  
      把`UserService`和`TitleComponent`从`src/app`移到`src/app/core`中
      
    * Create a `CoreModule` class to own the core material.
  
      创建`CoreModule`类来管理这些核心素材
  
    * Update the `AppRoot` module to  import `CoreModule`.
    
      修改`AppRoot`模块，使其导入`CoreModule`模块
  
  
negative.code:   Here's the refactored version of the `AppModule` along with the previous version.
  
    下面是`AppModule`重构完的版本与之前版本的对比。
    
  +makeTabs(
    `ngmodule/ts/src/app/app.module.2.ts,
     ngmodule/ts/src/app/app.module.1b.ts`,
     '',
    `src/app/app.module.ts (v2),
     src/app/app.module.ts (v1)`)
  
  :marked
    ### Improvements
  
  