x
 
<!DOCTYPE html>
<html>
<head>
  <style>.highlight{background-color: yellow}</style>
  <script type="text/javascript" src="../jquery/jquery.js"></script>
</head>
<body>
  <p><span>Look:</span> <span>This is some text in a paragraph.</span> <span>This is a note about it.</span></p>
  <script>$("p span").first().addClass('highlight');</script>
</body>
</html>