c语言程序设计题目求助

程序填空，不要改变与输入输出有关的语句。
输入一个正整数repeat (0<repeat<10)，做repeat次下列运算：
从键盘输入一批学生的成绩(以负数为结束标志)，计算平均分(保留2位小数)，并统计不及格成绩的个数。
输入输出示例：括号内为说明
输入
2 (repeat=2)
67 88 73 54 82 ?3
8 7 4 3 70 5 6 100 -1
输出
Grade average is 72.80,the number of fail is 1
Grade average is 25.38,the number of fail is 6

#include <stdio.h>
int main(void)
{
int fail, num;
int repeat, ri;
double grade, total;

scanf("%d",&repeat);
for(ri = 1; ri <= repeat; ri++){
scanf ("%lf", &grade);
/*---------*/
if(num > 0)
printf("Grade average is %.2f,the number of fail is %d\n", total/num, fail);
}
}

我的程序：
#include <stdio.h>
int main(void)
{
int fail, num;
int repeat, ri;
double grade, total;

scanf("%d",&repeat);
for(ri = 1; ri <= repeat; ri++){
scanf ("%lf", &grade);
total=0;
fail=0;
num=0;
while(grade>0){
total+=grade;
num++;
if(grade<60)
fail++;
scanf("%lf",grade);}
while(grade<0)
printf("Grade average is %.2f,the number of fail is %d\n", total/num, fail);
}
}
不知道错在哪里了，求助

---

修改如下:

//滚态型---------------------------------------------------------------------------
#include <stdio.h>
int main(void)
{
int fail, num;
int repeat, ri;
double grade, total;

scanf("%d",&repeat);
for(ri = 1; ri <= repeat; ri++){
scanf ("%lf", &grade);
total=0;
fail=0;
num=0;
while(grade>0){
total+=grade;
num++;
if(grade<60)
fail++;
scanf("%lf",&grade);} /*注意这里*/闭桥
if (num>0) /*注意这里*/
printf("Grade average is %.2f,the number of fail is %d\大猜n", total/num, fail);
}
}

//---------------------------------------------------------------------------

---

#include <迟宴stdio.h>
int main(void)
{
int fail, num;
int repeat, ri;
double grade, total;

scanf("%d",&repeat);
for(ri = 1; ri <野旦禅= repeat; ri++){
scanf ("%lf", &grade);
total=0;
fail=0;
num=0;
while(grade>0){
total+=grade;
num++;
if(grade<60)
fail++;
scanf("%lf",&grade);}
if(num > 0) 这里颂尘跟原题不符
printf("Grade average is %.2f,the number of fail is %d\n", total/num, fail);
}
}

---