local q = io.read("*n", "*l")
for iq = 1, q do
  local n = io.read("*n", "*l")
  local s = io.read()
  local t = {}
  for i = 1, n do
    local b = s:byte(i) - 64
    table.insert(t, b)
    while true do
      if 2 < #t and t[#t - 1] == 2 and t[#t - 2] == 1 and t[#t] == 2 then
        table.remove(t)
        table.remove(t)
        table.remove(t)
        table.insert(t, 2)
      else
        break
      end
    end
  end
  for i = 1, #t do t[i] = string.char(t[i] + 64) end
  print(table.concat(t))
end