anchor.diff:    我们把那些指令名加上了星号(\*)前缀。
   
     The asterisk is "syntactic sugar". It simplifies `ngIf` and `ngFor` for both the writer and the reader.
  -  Under the hood, Angular replaces the asterisk version with a more verbose `&lt;template>` form.
  +  Under the hood, Angular replaces the asterisk version with a more verbose `<template>` form.
   
     这个星号是一种“语法糖”。它简化了`ngIf`和`ngFor` —— 无论是写还是读。
   
  
positive.code:   using the built-in `ngOnInit` and `ngOnDestroy` [lifecycle hooks](lifecycle-hooks.html).
    Here it is in action:
  
    借助内建的`ngOnInit`和`ngOnDestroy`[生命周期钩子](lifecycle-hooks.html)，我们还能记录到组件的创建或销毁过程。
    下面是它的操作效果：
  
  figure.image-display
  
negative.code: 
    当这些`ngSwitch`的条件之一为真的时候，Angular把模板的内容插入到了DOM中。
  
    What does this have to do with `ngIf` and `ngFor`?  We didn't use a `<template>` tag with those directives.
  
    这和`ngIf`和`ngFor`有什么关系？很明显，我们在那些指令中并没有用到`<template>`标签。
  
  <a id="asterisk"></a>
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