#include<bits/stdc++.h>
using namespace std;


int main(){
    int x, T;

    cin >> T;

    for(int i = 0; i < T; i++){
        cin >> x;

        vector<int>arr(x);


        if(x % 2 == 0){
            for(int i = 0 ; i < x; i++){
                arr[i] = i + 2;
                arr[i+1] = i + 1;
                i = i+1;
            }
        }
        else{
            for(int i = 0; i < x; i++){
                arr[i] = i + 2;
                arr[i + 1] = i + 3;
                arr[i + 2] = i + 1;
                i += 2;
            }
        }

        for(auto a: arr){
            cout << a << " ";
        }
        cout << endl;

        arr.clear();

    }
}