那位大侠帮忙看看 返回为何不是 ab？

#include "stdafx.h"
#include <string.h>

main()
{

char x[30]="abcdefhijklmnopqrstuvwxyz";
char *q=x;

struct a
{
char y[2];
char y1[3];
char y2[4];
};

a a1;
memcpy(a1.y,q,sizeof(a1.y));
q=q+1;
memcpy(a1.y1,q,sizeof(a1.y1));
q=q+2;
memcpy(a1.y2,q,sizeof(a1.y2));

printf("%s",a1.y);

getchar();
return 0;
}