定义一个有20个元素的整型数组,分别求出下标为奇数和偶数的元素的平均值...答:int n[20]={1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20};float v1,v2;int i,n1,n2;v1=v2=n1=n2=0;for(i=0;i<20;i++){ if(i%2==0)v1+=n[i],n1++;else v2+=n[i],n2++;} v1/=n1;v2/=n2;printf("下标为偶数的元素平均值:%lf,下标为奇数...