c语言基础问题求解答

　输入某学生语文课程的成绩，输出该成绩的等级。判断规则为：如果成绩在90-100的范围内，则等级为A；若成绩在80-89的范围内，则等级为B；若成绩在70-79的范围内，则等级为C；若成绩在60-69的范围内，则等级为D；若少于60分，则等级为F。（要求：用switch语句实现。）

供参考：

#include <stdio.h>
int main()
{
    int grades,mark;
    scanf("%d", &grades);
    mark = (grades >= 0 && grades<=100 ? grades/10 : -1);
    switch (mark)
    {
        case 10:
        case 9: printf("the score is %d， is A\n",grades);
                break;
        case 8: printf("the score is %d， is B\n",grades);
                break;
        case 7: printf("the score is %d， is C\n",grades);
                break;
        case 6: printf("the score is %d， is D\n",grades);
                break;
        case 5:
        case 4:
        case 3:
        case 2:
        case 1:
        case 0:printf("the score is %d， is F\n",grades);
               break;
       default:printf("Error Enter!\n");
               break;
    }
    return 0;
}