anchor.diff:    **全部设置完了。** 来写点代码吧。
   
   .l-main-section#root-component  
  -:marked  
  +:marked
     ## Step 2: Our first Angular component
   
     Let's create a folder to hold our application and add a super-simple Angular component.
  
positive.code:   //- Nothing for ts.
  
  :marked
    ### Make some changes
    ### 做点改变
  
    Try changing the message to "My SECOND Angular 2 app".
  
  
negative.code:     >模板中只有一行HTML：“*My First Angular App*”。
  
      >A more advanced template could contain data bindings to component properties
      and might identify other application components which have their own templates.
      These templates might identify yet other components.
      In this way an Angular application becomes a tree of components.
  
  