T = gets.to_i

T.times do
  n = gets.to_i
  s = gets.chomp

  stack = []

  s.each_char do |c|
    stack << c

    while stack.size >= 3 && stack[-3] == 'A' && stack[-2] == 'B' && stack[-1] == 'B'
      stack.pop(3)
      stack << 'B'
    end
  end

  puts stack.join
end