import java.io.PrintWriter
import java.util.*
import kotlin.math.*

fun PrintWriter.solve() {
    val numCases = nextInt()
    case@ for (_i in 0 until numCases) {
        val n = nextInt()
        val s = nextLine()
        val stack = Stack<Char>()
        for (c in s) {
            stack.push(c)
            while (stack.size >= 3) {
                val c1 = stack.pop()
                val c2 = stack.pop()
                val c3 = stack.pop()
                val t = "$c3$c2$c1"
                if (t == "ABB") {
                    stack.push('B')
                } else {
                    stack.push(c3)
                    stack.push(c2)
                    stack.push(c1)
                    break
                }
            }
        }
        println(stack.joinToString(""))
    }
}

fun main() {
    Thread(null, {
        val writer = PrintWriter(System.out, false)
        writer.solve()
        writer.flush()
    }, "solve", abs(1L.shl(26)))
        .apply { setUncaughtExceptionHandler { _, e -> e.printStackTrace(); kotlin.system.exitProcess(1) } }
        .apply { start() }.join()
}

// region Scanner
private var st = StringTokenizer("")
private val br = System.`in`.bufferedReader()

fun next(): String {
    while (!st.hasMoreTokens()) st = StringTokenizer(br.readLine())
    return st.nextToken()
}

fun nextInt() = next().toInt()
fun nextLong() = next().toLong()
fun nextLine() = br.readLine()
fun nextDouble() = next().toDouble()
// endregion