Why i can't run it?

you have a too high error in your syntax, see my code of example! below:

<?php
$i = 5;

switch ($i) :
    case 0:
        echo '$i is 0.';
        break;
    case 1:
    case 2:
    case 3:
    case 4:
    case 5:
        echo '$i is somewhere between 1 and 5.';
        break;
    case 6:
    case 7:
        echo '$1 is either 6 or 7.';
        break;
    default:
        echo "I don't know how much \$i is";
        break;
endswitch;
?>

It doesnt work because $i == 5. And you don’t have case 5: in your code.

You only have case 2 and then your code skips to the situation when $i == 6

And what are you trying to acomplish with that code? Translated into english it would be like:

$i is 2
if $i is 2 chek if $i is either 3, 4, 5 and, if it isn't, do nothing!

It is obvious that, as long as $i == 2, it can’t simoultaneusly be 3, 4 or 5.

switch ($i) { case 0: echo ‘$i is 0.’; break; case 1: case 2: case 3: case 4: case 5: echo ‘$i is somewhere between 1 and 5.’; break;