#include<bits/stdc++.h>

using namespace std;

int main(){
  ios::sync_with_stdio(false);
  cin.tie(nullptr);
  int t;
  cin >> t;
  while(t>0){
    t--;
    int n;
    cin >> n;
    if(n%2==0){
      for(int i=1;i<=n;i++){
        if(i!=1){cout << " ";}
        if(i%2){cout << i+1;}
        else{cout << i-1;}
      }cout << "\n";
    }
    else{
      for(int i=1;i<=n-3;i++){
        if(i!=1){cout << " ";}
        if(i%2){cout << i+1;}
        else{cout << i-1;}
      }
      if(n!=3){cout << " ";}
      cout << n-1;
      cout << " " << n;
      cout << " " << n-2;
      cout << "\n";
    }
  }
  return 0;
}