刚刚做的，不过出现问题
#include "stdio.h"
main()
{int n=0,aver=0,a[10],i;
printf("input:");
for(i=0;i<10;i++)
{scanf("%d",&a[i]);
if(a[i]%2==0)
{aver+=a[i];
n++;}}
printf("%4.2f",aver/=n);
}