#include<stdio.h>
int main(void)
{
int i,number,grade,totalgrade=0,failure=0;
float avergrade;
printf("input how many grade you will input:");
scanf("%d",&number);
for(i=1;i<=number;i++)
{
printf("please input the #%d grade:",i);
scanf("%d",grade);
totalgrade=totalgrade+grade;
if(grade<60)
failure++;
}
avergrade=(float)totalgrade/number;
printf("the avergrade is %.2f\n",avergrade);
printf("the number of failures is:%d\n",failure);
return 0;
}

太粗心了……可以了~！谢谢！