#include<bits/stdc++.h>
using namespace std;
#define ll long long
#define endl '\n'
#define yes cout<<"YES"<<endl;
#define no cout<<"NO"<<endl;


int main ()
{
    ios_base::sync_with_stdio(0);
    cin.tie(0);

    int t; cin>>t;
    while(t--)
    {
        int n; cin>>n;

        if(n%2==0)
        {
             for(int i=1; i<=n; i++)
        {
             if(i%2!=0)
                cout<<i+1<<" ";
             else
                cout<<i-1<<" ";
        }
        cout<<endl;
        }

        else
        {
            for(int i=1; i<=n-3; i++)
            {
                if(i%2!=0)
                    cout<<i+1<<" ";
                else
                    cout<<i-1<<" ";

            }
            cout<<n-1<<" "<<n<<" "<<n-2<<endl;
        }

        }

        cout<<endl;

    return 0;
}