#!/bin/python3

import os
import sys


def rec(s,p1,p2,lev):
    if p2==len(s) and p1!=p2:
        lev+=1
        p2=p1=lev
    if p2==p1==len(s):
        return 
    else :
        for x in range(p1,p2+1):
            print(s[x], end ="")
        print(" ") 
        
        rec(s,p1,p2+1,lev)
        
# Complete the solve function below.
def solve(s):
  rec(s,0,0,0)
  return   

if __name__ == '__main__':
    fptr = open(os.environ['OUTPUT_PATH'], 'w')

    t = int(input())

    for t_itr in range(t):
        n = int(input())

        s = input()

        result = solve(s)
       # print(result)
        fptr.write('\n'.join(result))
        fptr.write('\n')

    fptr.close()