一樣的代碼為什么運行不成功?

<?php
require_once?'string.func.php';

//通過GD庫做驗證碼
//創建畫布
$width=200;
$height=40;
$image=imagecreatetruecolor($width,$height);
$white=imagecolorallocate($image,?255,?255,?28);
//畫布顏色
$black=imagecolorallocate($image,?0,?0,?0);
//畫筆顏色
//imagefill($image,0,0,$white);
//用填充矩形填充畫布
imagefilledrectangle($image,?1,?1,$width?-?1,?$heigth?-?1,?$white);

$type=1;
$length=4;
$chars=buildRandomString($type,$length);
$sess_name="verify";
$_SESSION[$sess_name]=$chars;

$fontfiles=array("msyh.ttc","msyhbd.ttc","msyhl.ttc","simfang.ttf","simhei.ttf","simkai.ttf","simsun.ttc");
for?($i=9;$i<$length;$i++){
????$size=mt_rand(14,18);
????$angle=mt_rand(-15,15);
????$x=5+$i*$size;
????$y=mt_rand(20,26);
????$fontfile="../fonts/".$fontfiles[mt_rand(0,count($fontfiles)-1)];
????$color=imagecolorallocate($image,?mt_rand(50,90),?mt_rand(80,200),?mt_rand(90,180));
????$text=substr($chars,$i,1);
????imagettftext($image,?$size,?$angle,?$x,?$y,?$color,?$fontfile,?$text);

}

header("content-type:image/gif");
imagegif($image);
imagedestroy($image);