title: How to add a new static method to existed Class?
body: <p>I've searched and read MSDN, but I only found out <a href="http://msdn.microsoft.com/en-us//library/bb383977.ASPX" rel="nofollow">how to add a instance method to a existed class</a>. </p>
  
  <p>Now, I want to add a static method to an existing class, like this:</p>
  
  <pre><code>String.myStaticMethod(....);
  </code></pre>
  
  <p>Can I do this? Is this not allowed in c#?</p>