#include <iostream>
#include <algorithm>
#include <set>
#include <map>
#include <vector>

using namespace std;

int main() {
    int t;
    cin >> t;
    while (t--) {
        int n, k;
        cin >> n >> k;
        for (int i = 0; i < k; i++)
            cout << "a";
        string s = "bca";
        for (int i = 0; i < n - k; i++)
            cout << s[i % 3];
        cout << endl;
    }
}