$adim1 = explode('<select', $source);
$adim2 = explode('</select>', $adim1[1]);
$select = $adim2[0];

preg_match_all('@<option value="(.*?)">(.*?)</option>@si', $select,  $veriler);
echo '<select name="select">';
for($i = 0; $i < count($veriler[1]); $i++){
   $value = $veriler[1][$i];
   $name = $veriler[2][$i];
   echo '<option value="' . $value . '">' . $name . '</option>';
}
echo '</select>';