description: You are given a sequence a_1, a_2, ..., a_n consisting of n pairwise distinct positive integers.
  
  Find \left⌊ \frac n 2 \right⌋ different pairs of integers x and y such that: 
  
    * x ≠ y; 
    * x and y appear in a; 
    * x~mod~y doesn't appear in a. 
  
  
  
  Note that some x or y can belong to multiple pairs.
  
  ⌊ x ⌋ denotes the floor function — the largest integer less than or equal to x. x~mod~y denotes the remainder from dividing x by y.
  
  If there are multiple solutions, print any of them. It can be shown that at least one solution always exists.
  
  Input
  
  The first line contains a single integer t (1 ≤ t ≤ 10^4) — the number of testcases.
  
  The first line of each testcase contains a single integer n (2 ≤ n ≤ 2 ⋅ 10^5) — the length of the sequence.
  
  The second line of each testcase contains n integers a_1, a_2, ..., a_n (1 ≤ a_i ≤ 10^6).
  
  All numbers in the sequence are pairwise distinct. The sum of n over all testcases doesn't exceed 2 ⋅ 10^5.
  
  Output
  
  The answer for each testcase should contain \left⌊ \frac n 2 \right⌋ different pairs of integers x and y such that x ≠ y, x and y appear in a and x~mod~y doesn't appear in a. Print the pairs one after another.
  
  You can print the pairs in any order. However, the order of numbers in the pair should be exactly such that the first number is x and the second number is y. All pairs should be pairwise distinct.
  
  If there are multiple solutions, print any of them.
  
  Example
  
  Input
  
  
  4
  2
  1 4
  4
  2 8 3 4
  5
  3 8 5 9 7
  6
  2 7 5 3 4 8
  
  
  Output
  
  
  4 1
  8 2
  8 4
  9 5
  7 5
  8 7
  4 3
  5 2
  
  Note
  
  In the first testcase there are only two pairs: (1, 4) and (4, 1). \left⌊ \frac 2 2 \right⌋=1, so we have to find one pair. 1~mod~4=1, and 1 appears in a, so that pair is invalid. Thus, the only possible answer is a pair (4, 1).
  
  In the second testcase, we chose pairs 8~mod~2=0 and 8~mod~4=0. 0 doesn't appear in a, so that answer is valid. There are multiple possible answers for that testcase.
  
  In the third testcase, the chosen pairs are 9~mod~5=4 and 7~mod~5=2. Neither 4, nor 2, appears in a, so that answer is valid.
solution:     import java.beans.DesignMode;
      import java.io.BufferedReader;
      import java.io.FileInputStream;
      import java.io.FileNotFoundException;
      import java.io.IOException;
      import java.io.InputStreamReader;
      import java.util.*;
      import java.util.concurrent.LinkedBlockingDeque;
      import java.util.concurrent.CompletableFuture.AsynchronousCompletionTask;
  
      import org.xml.sax.ErrorHandler;
  
      import java.io.PrintStream;
      import java.io.PrintWriter;
      import java.io.DataInputStream;
  
          public class Solution {
              //TEMPLATE -------------------------------------------------------------------------------------
              public static boolean Local(){
                  try{ 
                      return System.getenv("LOCAL_SYS")!=null;
                  }catch(Exception e){
                      return false;
                  }
              }   
  
              public static boolean LOCAL;
  
              static class FastScanner {
  
                      BufferedReader br;
                      StringTokenizer st ;
  
                      FastScanner(){
                          br =  new BufferedReader(new InputStreamReader(System.in));
                          st = new StringTokenizer("");
                      }
  
                      FastScanner(String file) {
  
                          try{
                              br =  new BufferedReader(new InputStreamReader(new FileInputStream(file)));
                              st = new StringTokenizer("");
                          }catch(FileNotFoundException e) {
                              // TODO Auto-generated catch block
                              System.out.println("file not found");
                              e.printStackTrace();
                          }
                          
                      }
                      String next() {
                          while (!st.hasMoreTokens())
                              try {
                                  st = new StringTokenizer(br.readLine());
                              } catch (IOException e) {
                              }
                          return st.nextToken();
                      }
  
                      int nextInt() {
                          return Integer.parseInt(next());
                      }
  
                      long nextLong() {
                          return Long.parseLong(next());
                      }
  
                      double nextDouble(){
                          return Double.parseDouble(next());
                      }
  
                      String readLine() throws IOException{
                          return br.readLine();
                      }
                  }
                                      
              static class Pair<T,X> {
  
                  T first;
                  X second;
                  
                  Pair(T first,X second){
                      this.first = first;
                      this.second = second;
                  }
  
                  @Override
                  public int hashCode(){
                      return Objects.hash(first,second);
                  }
  
                  @Override
                  public boolean equals(Object obj){
                      return obj.hashCode() == this.hashCode();
                  }
  
              }
  
          
          static PrintStream debug = null;      
          static long mod = (long)(Math.pow(10,9) + 7); 
      //TEMPLATE -------------------------------------------------------------------------------------END//
          public static void main(String[] args) throws Exception {
              
              FastScanner s = new FastScanner();
              LOCAL = Local();
              //PrintWriter pw = new PrintWriter(System.out);
              if(LOCAL){
                  s = new FastScanner("src/input.txt");
                  PrintStream o = new PrintStream("src/sampleout.txt");
                  debug = new PrintStream("src/debug.txt");
                  System.setOut(o);
              //  pw = new PrintWriter(o);
              } long mod = 1000000007;
  
          
              int tcr = s.nextInt();                  
              
  
              StringBuilder sb = new StringBuilder();
  
              
              for(int tc=0;tc<tcr;tc++){
                  int n = s.nextInt();
                  int arr[] = new int[n];
                  for(int i=0;i<n;i++){
                      arr[i] = s.nextInt();
                  }  
                  sort(arr);
                  int cnt = 0;
                  for(int i=1;i<n;i++){
                      sb.append(arr[i]+" "+arr[0]+"\n");
                      cnt++;
                      if(cnt >= (n/2)){
                          break;
                      }
                  }
              }
              print(sb.toString());
          }
  
  
          public static int check(int arr[],int k){
              
              int n = arr.length;
  
              if(k > (n/2)){
                  return arr[n/2];
              }
  
              int st = k-1;
              int e = n - k;
  
              for(int i=st+1;i<=e;i++){
                  if(arr[i] != arr[i-1]){return -1;}
              }
              return arr[st];
  
          }
  
  
          public static List<int[]> print_prime_factors(int n){
          
              List<int[]> list = new ArrayList<>();
              
              for(int i=2;i<=(int)(Math.sqrt(n));i++){
  
                  if(n % i == 0){
                      
                      int cnt = 0;
                      
                      while( (n % i) == 0){
                          n = n/i;
                          cnt++;
                      }
  
                      list.add(new int[]{i,cnt});
                  }
              }
  
              if(n!=1){
                  list.add(new int[]{n,1});
              }
  
              return list;
          }
  
          public static List<int[]> prime_factors(int n,List<Integer> sieve){
              List<int[]> list = new ArrayList<>();
              int index = 0;
              while(n > 1 && sieve.get(index) <= Math.sqrt(n)){
                  int curr = sieve.get(index);
                  int cnt = 0;
                  while((n % curr) == 0){
                      n = n/curr;
                      cnt++;
                  }
                  if(cnt >= 1){
                      list.add(new int[]{curr,cnt});
                  }
                  index++;
              }
              if(n > 1){
                  list.add(new int[]{n,1});
              }
              return list;
          }
  
          public static boolean inRange(int r1,int r2,int val){
              return ((val >= r1) && (val <= r2));
          }
  
          static int len(long num){
              return Long.toString(num).length();
          }
  
          static long mulmod(long a, long b,long mod)
          {
              long ans = 0l;
              
              while(b > 0){
                  long curr = (b & 1l);
                  if(curr == 1l){
                      ans = ((ans % mod) + a) % mod;
                  }
                  
                  a = (a + a) % mod;
  
                  b = b >> 1;
              }
  
              return ans;
          }
  
  
          public static void dbg(PrintStream ps,Object... o) throws Exception{
              if(ps == null){
                  return;
              }
              Debug.dbg(ps,o);
          }
  
          public static long modpow(long num,long pow,long mod){
  
              long val = num;
              long ans = 1l;
  
              while(pow > 0l){
                  
                  long bit = pow & 1l;
  
                  if(bit == 1){
                      ans = (ans * (val%mod))%mod;
                  }
  
                  val = (val * val) % mod;
                  pow = pow >> 1;
              }
  
              return ans;
  
          }
  
          public static char get(int n){
              return (char)('a' + n);
          }
  
          public static long[] sort(long arr[]){
              List<Long> list = new ArrayList<>();
              for(long n : arr){list.add(n);}
              Collections.sort(list);
              for(int i=0;i<arr.length;i++){
                  arr[i] = list.get(i);
              }
              return arr;
          }
  
          public static int[] sort(int arr[]){
              List<Integer> list = new ArrayList<>();
              for(int n : arr){list.add(n);}
              Collections.sort(list);
              for(int i=0;i<arr.length;i++){
                  arr[i] = list.get(i);
              }
              return arr;
          }
  
          // return the (index + 1)
          // where index is the pos of just smaller element
          // i.e count of elemets strictly less than num
          public static int justSmaller(long arr[],long num){
              //  System.out.println(num+"@");
              int st = 0;
              int e = arr.length - 1;
  
              int ans = -1;
  
              while(st <= e){
  
                  int mid = (st + e)/2;
  
                  if(arr[mid] >= num){
                      e = mid - 1;
                  }else{
                      ans = mid;
                      st = mid + 1;
                  }
  
              }
  
  
              return ans + 1;
  
          }
          public static int justSmaller(int arr[],int num){
              //  System.out.println(num+"@");
              int st = 0;
              int e = arr.length - 1;
  
              int ans = -1;
  
              while(st <= e){
  
                  int mid = (st + e)/2;
  
                  if(arr[mid] >= num){
                      e = mid - 1;
                  }else{
                      ans = mid;
                      st = mid + 1;
                  }
  
              }
  
  
              return ans + 1;
  
          }
          
          //return (index of just greater element)
          //count of elements smaller than or equal to num
  
          public static int justGreater(long arr[],long num){
              int st = 0;
              int e = arr.length - 1;
  
              int ans = arr.length;
  
              while(st <= e){
                  
                  int mid = (st + e)/2;
  
                  if(arr[mid] <= num){
                      st = mid + 1;
                  }else{
                      ans = mid;
                      e = mid - 1;
                  }
              }
  
              return ans;
  
          }
  
          public static int justGreater(int arr[],int num){
              int st = 0;
              int e = arr.length - 1;
  
              int ans = arr.length;
  
              while(st <= e){
                  
                  int mid = (st + e)/2;
  
                  if(arr[mid] <= num){
                      st = mid + 1;
                  }else{
                      ans = mid;
                      e = mid - 1;
                  }
              }
  
              return ans;
  
          }
  
          
  
          public static void println(Object obj){
              System.out.println(obj.toString());
          }
  
          public static void print(Object obj){
              System.out.print(obj.toString());
          }
  
          public static int gcd(int a,int b){
              if(b == 0){return a;}
              return gcd(b,a%b);
          }
  
          public static long gcd(long a,long b){
              if(b == 0l){
                  return a;
              }
  
              return gcd(b,a%b);
          }
  
          public static int find(int parent[],int v){
              if(parent[v] == v){
                  return v;
              }
              
              return parent[v] = find(parent, parent[v]);
          }
  
  
  
          public static List<Integer> sieve(){
          
                  List<Integer> prime = new ArrayList<>();
  
                  int arr[] = new int[1000001];
  
              Arrays.fill(arr,1);
  
              arr[1] = 0;
              arr[2] = 1;
  
              for(int i=2;i<1000001;i++){
                  
                  if(arr[i] == 1){
                      
                      prime.add(i);
  
                      for(long j = (i*1l*i);j<1000001;j+=i){
                          arr[(int)j] = 0;
                      }
                  }
              }
  
              return prime;
          }
  
          static boolean isPower(long n,long a){
              
              long log = (long)(Math.log(n)/Math.log(a));
  
              long power = (long)Math.pow(a,log);
  
              if(power == n){return true;}
  
              return false;
          }
  
  
          private static int mergeAndCount(int[] arr, int l,int m, int r)
          {
              // Left subarray
              int[] left =  Arrays.copyOfRange(arr, l, m + 1);
  
              // Right subarray
              int[] right = Arrays.copyOfRange(arr, m + 1, r + 1);
  
              int i = 0, j = 0, k = l, swaps = 0;
  
              while (i < left.length && j < right.length) {
                  if (left[i] <= right[j])
                      arr[k++] = left[i++];
                  else {
                      arr[k++] = right[j++];
                      swaps += (m + 1) - (l + i);
                  }
              }
              while (i < left.length)
                  arr[k++] = left[i++];
              while (j < right.length)
                  arr[k++] = right[j++];
              return swaps;
          }
  
          // Merge sort function
          private static int mergeSortAndCount(int[] arr, int l,int r)
          {
  
              // Keeps track of the inversion count at a
              // particular node of the recursion tree
              int count = 0;
  
              if (l < r) {
                  int m = (l + r) / 2;
  
                  // Total inversion count = left subarray count
                  // + right subarray count + merge count
  
                  // Left subarray count
                  count += mergeSortAndCount(arr, l, m);
  
                  // Right subarray count
                  count += mergeSortAndCount(arr, m + 1, r);
  
                  // Merge count
                  count += mergeAndCount(arr, l, m, r);
              }
  
              return count;
          }
  
          static class Debug{
              //change to System.getProperty("ONLINE_JUDGE")==null; for CodeForces
              public static final boolean LOCAL = System.getProperty("ONLINE_JUDGE")==null;
  
              
  
              private static <T> String ts(T t) {
                  if(t==null) {
                      return "null";
                  }
                  try {
                      return ts((Iterable) t);
                  }catch(ClassCastException e) {
                      if(t instanceof int[]) {
                          String s = Arrays.toString((int[]) t);
                          return "{"+s.substring(1, s.length()-1)+"}\n";
                      }else if(t instanceof long[]) {
                          String s = Arrays.toString((long[]) t);
                          return "{"+s.substring(1, s.length()-1)+"}\n";
                      }else if(t instanceof char[]) {
                          String s = Arrays.toString((char[]) t);
                          return "{"+s.substring(1, s.length()-1)+"}\n";
                      }else if(t instanceof double[]) {
                          String s = Arrays.toString((double[]) t);
                          return "{"+s.substring(1, s.length()-1)+"}\n";
                      }else if(t instanceof boolean[]) {
                          String s = Arrays.toString((boolean[]) t);
                          return "{"+s.substring(1, s.length()-1)+"}\n";
                      }
                      try {
                          return ts((Object[]) t);
                      }catch(ClassCastException e1) {
                          return t.toString();
                      }
                  }
              }
              private static <T> String ts(T[] arr) {
                  StringBuilder ret = new StringBuilder();
                  ret.append("{");
                  boolean first = true;
                  for(T t: arr) {
                      if(!first) {
                          ret.append(", ");
                      }
                      first = false;
                      ret.append(ts(t));
                  }
                  ret.append("}");
                  return ret.toString();
              }
              private static <T> String ts(Iterable<T> iter) {
                  StringBuilder ret = new StringBuilder();
                  ret.append("{");
                  boolean first = true;
                  for(T t: iter) {
                      if(!first) {
                          ret.append(", ");
                      }
                      first = false;
                      ret.append(ts(t));
                  }
                  ret.append("}\n");
                  return ret.toString();
              }
              public static void dbg(PrintStream ps,Object... o) throws Exception {
                  if(LOCAL) {
                      System.setErr(ps);
                      System.err.print("Line #"+Thread.currentThread().getStackTrace()[2].getLineNumber()+": [\n");
                      for(int i = 0; i<o.length; i++) {
                          if(i!=0) {
                              System.err.print(", ");
                          }
                          System.err.print(ts(o[i]));
                      }
                      System.err.println("]");
                  }
              }
          }
  
      }