anchor.diff:    That's not a problem. When three modules all import Module 'A', 
     Angular evaluates Module 'A' once, the first time it encounters it, and does not do so again. 
     
  -  不会有问题。当三个模块全都导入模块'A'时，Angular只会加载一次模块'A'，也就是首次遇到时，之后就不会这么做了。
  +  不会有问题。当三个模块全都导入模块'A'时，Angular只会首次遇到时加载一次模块'A'，之后就不会这么做了。
   
     That's true at whatever level `A` appears in a hierarchy of imported modules.
     When Module 'B' imports Module 'A', Module 'C' imports 'B', and Module 'D' imports `[C, B, A]`,
  
positive.code:   But "almost" isn't good enough for routed applications.
    
    `AppComponent`的注入器是根注入器的*子级*，注入器层次中的下一级。
    这对于不用路由器的应用来说*几乎是*整个应用了。
    但这个“几乎”对于带路有的应用仍然是不够的。
  
    `AppComponent` services don't exist at the root level where routing operates. 
  
negative.code: :marked
    #### What kinds of modules should I have and how should I use them?
    
    #### 有哪些类型的模块？我应该如何使用它们？
  
    Every app is different and developers have varying levels of experience and comfort with the available choices.
    Some suggestions and guidelines appear to have wide appeal.
  