请问一个关于id的有关问题

请教一个关于id的问题
<!DOCTYPE html>
<html>
<head>
  <script type="text/javascript" src="/jquery/jquery.js"></script>
</head>

<body>

<p>This is a paragragh.</p>
<p>This is a paragragh.</p>
<p>This is a paragragh.</p>
<p id="abc">This is a paragragh.</p>
<p>This is a paragragh.</p>
<p>This is a paragragh.</p>

<script>
var s = "abc";
$("p").not("#s").css('background-color', 'red');
</script>

</body>
</html>


------解决方案--------------------
$("p").not("#"+s).css('background-color', 'red');
s是变量。。。要么这样
$("p").not("#abc").css('background-color', 'red');