我正试图根据学生的分数生成一份报告书。在表格中，我有一个复选框，如果学生缺席，教师可以从中打勾，如果是这种情况，则标记的值必须更改为AB，注解为缺席，而它可以将值更改为“AB”，这段代码不能提供学生“缺席”的注解，而是将“未通过”作为注解。2我应该在代码中修改什么？

if (isset($_POST['absent']) && (empty($mark)))
    {
        $mark="AB";
        $comment="Absent";
    }
    if($mark < 101 && $mark >=0)
    {   $comment="";
        if($grade > 9){
            $score="";
            if($mark >=75 and $mark <= 100 ){
                $score=1;
            $comment="Distinction";
            }else if($mark >= 70 and $mark <=74){
                $score=2;
            $comment="Distinction";
            }else if($mark >= 65 and $mark <= 69 ){
                $score=3;
            $comment="Merit";
            }else if($mark >= 60 and $mark <=64){
                $score=4;
            $comment="Merit";
            }else if($mark >= 55 and $mark <= 59){
                $score=5;
            $comment="Credit";
            }else if($mark >= 50 and $mark <= 54){
                $score=6;
            $comment="Credit";
            }else if($mark >= 45 and $mark <= 49){
                $score=7;
            $comment="Pass";
            }else if($mark >= 40 and $mark <= 44){
                $score=8;
            $comment="Pass";
            }else if($mark >= 0 and $mark <=39){
                $score=9;
            $comment="Fail";
            }else if($mark=="AB"){
                $comment="Absent";
            }