#include<bits/stdc++.h>
using namespace std;
#define ll long long
#define loop(i,a,b) for(ll i=a;i<b;i++)
#define pb push_back
#define fast ios_base::sync_with_stdio(false);cin.tie(NULL);
#define ff first
#define ss second
#define vc vector

int main()
{
    ll t;
    cin>>t;
    while(t--)
    {
		int n,k;
		cin>>n>>k;
		
		char arr[]={'a','b','c'};
		
		k--;
		
		loop(i,0,k)
		cout<<'a';
		
		loop(i,0,n-k)
		cout<<arr[i%3];
		
		cout<<endl;
		
		

    }
}
