$score=81;
switch ($score)
{
case "$score">90&&"$$score"<=100:
echo"优秀
";
break;
case "$score">80&&"$score"<=90:
echo"优良
";
break;
case "$score">=60&&"$score"<=80:
echo"中等
";
break;
case "$score">=0&&"$score"<60:
echo"不及格
";
break;
default:
echo"成绩设置有误
";
}