title: BSD sed: extra characters at the end of d command
body: <p>I use sed command on mac OS, following is the text.</p>
  
  <pre><code>$ cat pets.txt 
  This is my cat
    my cat's name is betty
  This is your dog
    your dog's name is frank
  This is your fish
    your fish's name is george
  This is my goat
    my goat's name is adam
  </code></pre>
  
  <p>when I run: (BSD sed)</p>
  
  <pre><code>$ sed '3,6 {/This/d}' pets.txt
  </code></pre>
  
  <p>It show error:</p>
  
  <pre><code>sed: 1: "3,6 {/This/d}": extra characters at the end of d command
  </code></pre>
  
  <p>what's wrong with it? when I use <code>gsed(GNU sed)</code>, it works well.</p>