<?php
if(isset($_GET['score'])){
    $score = $_GET['score'];
}
else{
    $score = -1;
    echo "请输入成绩!<br/>"; 
}
if($score>=90&&$score<=100){
    echo "成绩优秀";
}elseif($score>=80&&$score<=90){
    echo "成绩良好";
}elseif($score>=60&&$score<=80){
    echo "成绩及格";
}elseif($score>=0){
    echo "成绩不及格";
}
?>