#include"stdio.h"
#include"stdlib.h"
#include"time.h"
main()
{
    int a,b,i=1,shang,yu,t=0,w4=0,w5;
    system("cls");
    srand((int)time(0));
    while(i<=10)
    {a=rand()%10;
    b=rand()%10;
    if(a<b)
        continue;
    else
        if(a%b!=0)
            continue;
        else
    {printf("%d/%d=",a,b);
    scanf("%d",&shang);
   
    }
    if(shang==a/b)
    {    printf("回答正确!\n");
    w4+=1;}
    else
    {    printf("回答错误!\n");
    w5+=1;}
    i=w4+w5;
    }
   
}

1.没考虑b为0的情况
2.w5没初始化

#include"stdio.h"
#include"stdlib.h"
#include"time.h"
main()
{
    int a, b, i = 1, shang, yu, t = 0, w4 = 0, w5=0;  //w5 线赋值 0
    system("cls");
    srand((int)time(0));
    while (i <= 10)
    {
        a = rand() % 10;
        b = rand() % 10;
        if (a > b && b!=0) // b为分母不能为0，否则程序崩溃
        {
            if (a%b != 0)
                continue;
            else
            {
                printf("%d/%d=", a, b);
                scanf("%d", &shang);

            }
            if (shang == a / b)
            {
                printf("回答正确!\n");
                w4 += 1;
            }
            else
            {
                printf("回答错误!\n");
                w5 += 1;
            }
            i = w4 + w5;
        }
    }
}

还有些 写法不标准的，如 #include"stdio.h"