#include <iostream>
#include <cstring>
#include <algorithm>
using namespace std;
int n,k,T;
char a[]={'a','b','c','d','e','f','g','h','i','j','k','l','m','n',
'o','p','q','r','s','t','u','v','w','x','y','z'};
int main()
{
cin>>T;
while(T--)
{
cin>>n>>k;
string s;
int d = n/k;
int c = n%k;
for(int i=0;i<d;i++)
for(int j=0;j<k;j++)
s+=a[j];
for(int i=0;i<c;i++)
s+=a[i];
cout<<s<<endl;
}
return 0;
}