anchor.diff:    <a href="https://developer.mozilla.org/en-US/docs/Web/Guide/CSS/Getting_started/Selectors" target="_blank">standard CSS selector</a>
     predicate that filters the same way as a jQuery selector.
   
  -  **`By`**类是一个Angular测试工具，它生成有用的predicate。
  +  **`By`**类是Angular测试工具之一，它生成有用的predicate。
     它的`By.css`静态方法产生一个<a href="https://developer.mozilla.org/en-US/docs/Web/Guide/CSS/Getting_started/Selectors" target="_blank">标准CSS选择器</a>
     predicate，与JQuery选择器相同的方式过滤。
   
  
positive.code:   The `fakeAsync` function is another of the Angular testing utilities.
  
    注意，在`it`的参数中，`async`被`faceAsync`替换。
    `fakeAsync`是另一个Angular测试工具。 
  
    Like [async](#async-fn-in-it), it _takes_ a parameterless function and _returns_ a parameterless function
    which becomes the argument to the  Jasmine `it` call. 
  
negative.code:   The `TestBed.createComponent` is a synchronous method. 
    It assumes that everything it could need is already in memory.
  
    `TestBed.createComponent`时一种同步的方法。它假设所有它需要的资源已经全部在内存。
  
    That has been true so far. 
    Each tested component's `@Component` metadata has a `template` property specifying an _inline templates_.
  