anchor.diff:    Imagine that our `HighlightDirective` did truly wonderous things.
     We graciously made a gift of it to the world. 
     
  -  假想一下，我们的`HighlightDirective`真是一个好东西。
  +  假想一下，`HighlightDirective`真是一个好东西。
     我们优雅的把它当作礼物送给全世界。
     
     To our surprise, some people &mdash; perhaps naively &mdash;
  
positive.code:   as it is does when we bind to the `myHighlight` property of the `HighlightDirective`, 
    
    如果它出现在了**方括号**([ ])中，并且出现在等号(=)的**左侧**，它就是一个*目标*……
    就像在我们绑定到`HighlightDirective`的`myHighlight`属性时所做的那样。
  +makeExample('attribute-directives/ts/app/app.component.html','pHost')(format=".")
  :marked
    The 'color' in `[myHighlight]="color"` is a binding ***source***.
  
negative.code:   Earlier we declared the `highlightColor` property to be an ***input*** property of our
    `HighlightDirective`
    
    之前, 我们曾把`highlightColor`定义为`HighlightDirective`指令的一个***input***属性。
   
    We've seen properties in bindings before. 
    We never had to declare them as anything. Why now?
    
    以前也见过属性绑定，但我们从没有定义过它们。为什么现在就不行了？
    
    Angular makes a subtle but important distinction between binding **sources** and **targets**.
    
  