switch case加条件语句(非等值) php

<?php
$s_level=rand(1,6);
echo $s_level.'<br/>';
switch(true){
case $s_level<3 :
echo 'less than 3';
break;
case $s_level>5 :
echo 'more than 5';
break;
default :
echo 'ok';
}
?>