title: Regex - match a string, but only where the next word is not 'x'
body: <p>If I have this string:</p>
  
  <p>"The quick brown fox jumped over the lazy dog.  What a nice brown fox that is."</p>
  
  <p>What regex would I use to match the text 'brown fox' but not where the following word is 'that', i.e. (matches in italic):</p>
  
  <p>"The quick <em>brown fox</em> jumped over the lazy dog.  What a nice brown fox that is."</p>